Chief Seattle’s Speech Summary by Chief Seattle’s

Chief Seattle’s Speech Summary by Chief Seattle’s

Chief Seattle who was the native American leader of the Suquamish and Duwamish tribes of Washington, delivered his speech in January of 1854. His speech was given to his people when American colonisers wanted to buy native land of his tribe and in return offered them amnesty, and the right to live there. As an old Chief who had seen natives killed, he reluctantly accepted the offer since he believed, turning it down will only result in the total annihilation of his tribe.

His speech was both consolatory in nature, helping his people to understand what was going on, their weak position in the political climate and helping them to understand the transition they were now forced to make. He even mentions how Canada’s borders are now being controlled by King George but their ‘Big Chief and ‘Father’ is now a White man who sits in Washington. The speech delivered by Seattle is considered a legendary speech by Native Americans as it sums up their plight in front of American Colonisers.

The speech delivered by Seattle was published in the Seattle Sunday Star, October 29, 1887, by Dr. Henry A. Smith. Smith is said to have taken notes as Chief Seattle spoke in the Suquamish dialect, and then transcribed the text in English from his notes. The last two sentences of the text here given have been considered for many years to have been part of the original, but are now known to have been added by an early 20th century historian and ethnographic writer, A.C. Ballard. The most important fact to note is that there is no verbatim transcript in existence.

All known texts are second hand. Smith makes it very clear that his version is not exact a copy, but rather the best he could put together from notes taken at the time. There is an undecided historical argument on which native dialect the Chief would have used, Duwamish on Suquamish. Either way all agree the speech was translated into Chinook Jargon on the spot, since Chief Seattle never learned to speak English.

Chief Seattle’s Speech Summary Introduction

Chief Seattle was an important figure in the early American History. He was the Chief of the Suquamish and Duwamish tribes, fighting for the rights of his native people in the face of American Colonisers. He was the powerful leader of Red Indians in the Puget sound area. He wanted to put his people at ease and corporate with the White settlers at the same time. White people get the land they wanted from Seattle and Seattle brings comfort to his own tribe by talking to them about the real nature of living to them.

The speech which was delivered by Seattle in January, 1854, was a formal response to Governor Stevens’ proposal’ to acquire the land of Red Indians. Smith published the speech from what he claimed were his notes taken at the time.

According to H.A. Smith, Chief Seattle is in front of a crowd gathered by Governor Isaac Stevens to discuss the sale of native land to the white men. While delivering his speech, Seattle thanks the white men for showing sympathetic attitude and generosity by allowing him and his people a place to live peacefully and comfortably.

Chief Seattle begins his speech with a positive change in the native Red Indian’s fives. He says that nature has been kind and sympathetic for his people for many centuries. But the situation will not remain same. He feels that the things which seem to be fine at present, but the scenario will change in the future as the Great Chief (George Washington, the first President of the United States of America) wishes to put the land of the native Americans with words of feigned ‘good will and friendship.’ Seattle says that the Great Chief is in little need of their help and friendship, as his people (the whites) are strong and powerful if compared to the natives, but it is the greatness of the Washington Chief as he has extended the hand of friendship.

Then the Chief Seattle recollects the time when his people were large in number, but now, their number has been reduced. He compares the Whites to the grass that covers the vast prairies, large in number. His people are few and they resemble the scattering trees of a storm swept plain. Seattle says that the proposition seems to be just, kind and generous as the Red man no longer has rights. In Seattle’s opinion, the offer appears to be wise since the native Americans are less in number and don’t require a vast territory.

Once again, Seattle compares the past situation of the tribal people when they were in their glorious phase to the waves of a wind-ruffed sea. He means to express how lively and energetic his people were then. But, instead of mourning over their untimely decay, he wants to look forward. Then, Seattle points out that youth is impulsive and the youngmen often indulge in revengeful acts considering them to be gainful. During war or other revengeful acts, they even lose their own lives, but their families have to bear the loss. The members of their families have to suffer from utter sufferings and sorrows. So, he suggests that his natives and the white settlers should make a peaceful atmosphere and they should never think of hostility.

Chief Seattle mentions George Washington as their ‘good father’ and says that their ‘good father’ has promised his natives if they surrender or sell their land to the White settlers, he will protect them from foreign enemies like Haidas and Tsimshians. His vigorous, energetic and brave warriors will provide them strength. Seattle also hopes that the White Chiefs brave men will provide the natives strengths. His ship would fill their harbours so that Hidas and Tsimshians will cease to frighten the natives. Then, in true sense, he would be their father and they would be his children.

But then a doubt lingers in the mind of Seattle and he feels that God of the White people is not their God. The God of the Whites loves and protects his people and hates the tribal people (the red children). He has forsaken his Red children. Seattle, then, refers to his own God, the Great Spirit who also seems to be forsaking them. His natives seem to be orphans who can look nowhere for help. Thus he remarks that they are two distinct races having separate origins and separate destinies. A great difference is found between the whites and his people.

Then, Seattle praises the sacredness which is related not only, with the ashes of their ancestors but also with this land which is their resting place. The natives love to stay in the land where their ancestors’ memories are alive whereas the whites wander far from their ancestors’ graves. He, then, says that the white man’s religion was inscribed upon tablets of stone by the iron fingers of their God so that they could not forget whereas the Red man could never comprehend or remember it.

But the religion of his people is the traditions of their ancestors. It constitutes the dreams of their old men and is written in the hearts of their people. The ancestors of the Europeans (after their death) cease to love them and the land of their nativity, but on the other hand, the ancestors (or the dead) of his race never forget their beautiful world that gave them their being. They still love its valleys, rivers, magnificent mountains and lakes. Even after their death, they long to show their affection to the gloomy hearts and often return to visit, guide, console and comfort them.

After this, Chief Seattle says that there is great difference between these two races (native Americans and the Whites). They can not develop any attachment with each other. They can not live together. Hence he compares them like day and night. The Red men flee away at the approach of the whites as the morning mist flees before the morning sun. But the white man’s poposition seems fair and he thinks that his people will except it. He hopes that then they will dwell apart in place.

Then, Seattle says that it is a matter of little importance where his people the remnant of their days, but it is certain that the number of his people will reduce. No single star of hope can be seen hovering above his horizon. The winds moan and grain fate follows them. Their situation is similar to a wounded doe that is being hunted down. In a few more year, the race of his people will disappear. He also warns that some day the white settlers too will face the same destiny. It is the order of nature that everything will see decline sooner or later. As the Red tribal people of America have been reduced to their meager existence, the white people will see the same fate whatever distant it may be. Though God has favoured the white people more than the tribal people, they can not be exempted from the common destiny of decay and doom.

Chief Seattle says that they will accept the proposal of acquisition of land of the Governor of Washington but puts forward a condition-that they will not be prevented from visting the ashes (tombs) of their ancestors as the land is sacred to them. Every hill, every valley, every plain and even rivers which are known as lifeless, are sacred to his people.

Seattle says that the native Americans would be transported to a reality beyond what is felt by the senses. The shores, the pathless woods, the field would never be empty of their spirits. This land will make them eternal. They will be a part of land forever. Their death would not be death but only a gateway to the eternal world. They will only change their world and hence will become immortal. He ends his speech with the assertion that there is no death, only a change of world.

Chief Seattle’s Speech Summary Stanzawise Word-Meanings

Yonder = at a distance, but within a view. Compassion = a sensation of scftrow excited by the distress or misfortunes; pity. External = everlasting; endless. Untold = not related; not revealed. Overcast = filled or abounding with clouds. The Great chief at Washington = George Washington. White Chief = Governor Isaac Stevens. Greeting = expression of kindness or joy. Vast prairies = large open area of grassland specially found in North America. Resemble = to be like or similar to. Scattering = a small number of something. Presume = to suppose or assume.

Red man = native American. Extensive = expanded; large. Ruffled = disturbed. Dwell on = linger over. Mourn over = grieve over. Untimely decay = destroyed before the usual time. Reproach = to attribute blame to. Paleface = a derogatory term for a white person (said to have been used by North American Indians). Impulsive = without forethought; actuated by impulse or by transient feelings. Disfigure = to mar the figure of. Relentless = stern; insensible to the distress of others. Restrain = to hold back from. Push = to drive or impel by force or pressure. Hostilities = animosities. Bristling = vigorous and energetic. Harbors = seaports. Haidas = members of a seafaring group of North American Indian who lived on the Pacific coast of British Columbia and Southwestern Alaska.

Tsimshians = members of a penutian people who lived on rivers in British Columbia. For-saken = left entirely; abandoned. Waxstronger = spread from one to another area. Ebbing = receding; going out; falling. Receding = moving back; retreating; withdrawing. Teeming multitudes = a large number of people. Firmament = the region of the air; the sky or heavens. Distinct = different. Ashes = the remains of the human body when burnt, or when returned to dust by natural decay. (Perhaps here it is used for tombs). Hallowed = sacred; worthy of religious veneration. Iron finger = finger of God. Comprehend = to take into the mind; to understand.

Sachemes = chiefs of a tribe of the American Indian. Portals = doors or gates; ways of entrance or exit. Verdant = covered with growing plants or grass; green; fresh; flourishing. Magnificent = grand in appearance. Sequestered = secluded. Vales = valleys. Yearn = dream of, a strong longing. Fond = loving; affectionate. Flees = makes a quick exit. Mist = fog. Remnant = remaining; yet left. Hovers = hangs fluttering in the air. Horizon = the apparent junction of the earth and sky. Moan = to make a low prolonged sound of grief or pain; to groan softly and continuously. Trail = track, path. Stolidly = without being upset. Doom = destruction. Untimely fate = premature death or doom. Decay = destruction; death. Ponder = to think; to muse. Privilege = a peculiar benefit, advantage, or favour. Molestation = disturbance; annoyance. Estimation = an approximate calculation; opinion. Grove = a small growth of trees. Swelter = to be overcome and faint with heat. Eventide = the time of evening; evening. Myth = a traditional story accepted as history. Solitude = state of being alone; a lovely life; loveliness. Throng = a multitude of persons or of living beings; a crowd.

Chief Seattle’s Speech Summary About the Writer

Chief Seattle or Sealth was a leader of the Suquamish and Duwamish Native American tribes. He was a prominent figure among his people. He pursued a path of accommodation to white settlers, forming a personal relationship with David Swinson ‘Doc’ Maynard. Maynard was an advocate of Native American rights whose friendship with Chief Seattle was important in the formation of city of Seattle. When the first plots for the village were filed on May 23, 1853, due to Maynard’s prompting, it was for the ‘Town of Seattle.’

. Beyond leadership skills and the gift of oratory, Chief Seattle had the desire for the two vastly different cultures to coexist in peace. He both observed and played a part in the birth of a small village named after him, that has since grown into a large metropolis known for its innovation, openness, diversity and love for creation.

Chief Seattle was born around 1786 on or near Blake Island, Washington near present day Seattle. His father, Schweabe, was a leader of the Suquamish tribe of Agate Pass, between Brainbridge Island and the mainland of Washington state’s Kitsap Peninsula across Puget Sound from the present city of Seattle. Seattle’s mother was Sholitza, the daughter of a Duwamish chief, from near the lower Green River area. As the line of descent traditionally ran through the mother, Seattle was considered Duwamish. Both the Suquamish and Duwamish are Coast Salish people. Seattle’s given name at birth was Sealth.

Seattle grew up speaking two different dialects of Lushootseed and was blessed with skill-sets from the two different tribes. Once he was made the chief of the Duwamish tribe. It is believed that he sighted the ships from the Vancouver expedition, as they explored the region around the Salish Sea, which is now known as Puget Sound. From a very young age, he earned the standing of an authoritative personality and was known for his leadership qualities.

By 1833, when the Hudson’s Bay Company founded Fort Nisqually near the head of Puget Sound, Seattle had a solid reputation as an intelligent and formidable leader with a compelling voice. He was also known as an orator and when he addressed an audience, his voice is said to have carried from his camp to the Stevens Hotel at First and Marrion, a distance of three-quarters of a mile. He was tall and broad for a Puget Sound native at nearly six feet; Hudson’s Bay Company traders gave him to nickname LeGros (The Big One).

In 1847, Seattle helped lead the Suquamish in an attack upon the Chemakum stronghold of Tsetsibus, near Port Townsend, that effectively wiped out this rival group. The death of one of his sons during the raid affected him deeply, for not long after that he was baptized into the Roman Catholic Church and give the baptismal name Noah. He is believed to have received his baptism by the Oblates of Mary Immaculate at their Joseph of Newmarket Mission, founded near the new settlement of Olympia in 1848. This conversion was a turning point for Seattle and the Duwamish, as it marked the end of his fighting days and his emergence as leader known as ‘friend to the whites’.

White settlers began arriving in the Puget Sound area in 1846, and in the area that later became the city of Seattle, in 1851. Seattle welcomed the settlers and sought out friendships with those with whom he could do business. His initial contact was with San Francisco merchant, Charles Fay, with whom he organized a fishery on Elliott Bay in the summer of 1851. When Fay returned to San Francisco, Chief Seattle moved South to Olympia. Here he took up with David S. ‘Doc’ Maynard.

Seattle helped protect the small band of settlers. Because of his friendship and assistance, it was Maynard who advocated for naming the settlement ‘Seattle’ after Chief Seattle. When the first plots for the village were filed on May 23, 1853, it was for the ‘Town of Seattle’.

Seattle served as native spokesman during the treaty council held at Point Elliott (later Mukilteo), from December 27, 1854, to January 9, 1855. While he voiced misgivings about ceding title to some 2.5 million acres of land, he understood the futility of opposing a force so much larger than his own people. In signing the treaty and retaining a reservation for the suquamish but not for the Duwamish, he lost the support of the latter. This unhappiness soon led to the Yakima Indian War of 1855-1857. Seattle kept his people out of Battle ofi Seattle (1856). Afterwards he unsuccessfully sought clemency for the war leader, Leschi. On the reservation, he attempted to curtail the influence of whiskev sellers and he interceded between the whites and the natives. Off the reservation, he participated in meetings to resolve native disputes.

Seattle maintained his friendship with Maynard and cultivated new relationships with other settlers. He was unwilling to lead his tribe to the reservation established, since mixing Duwamish and Snohomish was likely to lead to bloodshed. Maynard persuaded the government of the necessity of allowing Seattle to remove to his father’s longhouse on Agate Passage, ‘Old Man House’. Seattle frequented the town named after him. He died on June 7, 1866, on the Suquamish reservation at Port Madison, Washington.

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    A: Gay Lussac’s Law-Avogadro’s Law-Mole concept
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Selina Concise Chemistry Class 8 ICSE Solutions – Physical and Chemical Changes

Selina Concise Chemistry Class 8 ICSE Solutions – Physical and Chemical Changes

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ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 2 Physical and Chemical Changes. You can download the Selina Concise Chemistry ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Chemistry for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 2 Physical and Chemical Changes

Exercise

Question 1.
Define:
(a) a physical change, (b) a chemical change.
Answer:
(a) Physical Change: A physical change is a temporary change in which no new substance is formed and the chemical composition of the original substance remains the same, even though its physical properties like colour, state, shape, size etc. might change.
(b) Chemical Change: A chemical change is permanent change in which new substances are formed whose chemical composition and physical and chemical properties are different from those of in original substance.

Question 2.
Classify the following as a physical or a chemical change.
(a) Drying of wet clothes
(b) Manufacture of salt from sea water
(c) Butter getting rancid
(d) Boiling of water
(e) Burning of paper
(f) Melting of wax
(g) Burning of coal
(h) Formation of clouds
(i) Making of a sugar solution
(j) Glowing of an electric bulb
(k) Curdling of milk
Answer:
Physical change
(a) Drying of wet clothes
(b) Manufacture of salt from sea water
(d) Boiling of water
(f) Melting of wax
(h) Formation of clouds
(i) Making of a sugar solution
(j) Glowing of an electric bulb.
Chemical change
(c) Butter getting rancid
(e) Burning of paper
(g) Burning of coal
(k) Curdling of milk

Question 3.
Fill in the blanks.
Answer:
(a) The process of a liquid changing into a solid is called freezing.
(b) A change, which alters the composition of a substances, is known as a chemical change.
(c) There is no change in the composition of the substance during a physical change.
(d) The reaction in which energy is evolved is called exothermic reaction.

Question 4.
Given reason:
(a) Freezing of water to ice and evaporation of water are physical changes.
(b) Burning of a candle is both a physical and chemical change.
(e) Burning of paper is a chemical change.
(d) Cutting of a cloth piece is a physical change, though it cannot be reversed.
Answer:
(a) Freezing of water to ice and evaporation of water are physical change because water can be brought back to its original (liquid) form by

  1. We can heat the ice to bring it back to water.
  2. We can cool down the vapours to bring it back to water.

(b) When a candle is lighted, some of the solid wax first melts and turns into liquid, then it turns into vapours to produce a flame. New substances CO2 and H2O vapours are formed alongwith the evolution of light and heat energy. This shows a chemical change. When some of the molten wax drops to the floor, it again solidifies. Which shows a physical change. Thus the melting of candle wax is a physical change and the production of CO2 and H2O represents chemical change.

(c) When a piece of paper is burnt a new substance ash is produced. Even when the burning is stopped, the ash cannot be changed back into paper. This shows that the formation of the ash from paper is a permanent and irreversible change.

(d) Because it does not change chemical composition of cloth and the change is only in the state, size, shape, colour, texture or the smell of some or all of the substances that undergo physical change.

Question 5.
Give four difference between physical and chemical changes.
Answer:
The differences are Physical and Chemical Changes:
Physical change

  1. In a physical change no new substance is formed and the chemical composition of substance remains same. There are changes only in physical properties and state.
  2. Temporaiy change which can be reversed by simple physical methods.
  3. Weight of original substance doesn’t change
  4. Energy like heat, light etc. may or may not be absorbed or released

Chemical change

  1. In a chemical change new substance with entirely different chemical composition and properties is formed.
  2. Permanent change and irreversible
  3. Weight of original substances may increase or decrease
  4. Energy like heat, light etc. are given out or absorbed.

Selina Concise Chemistry Class 8 ICSE Solutions – Chemical Reactions

Selina Concise Chemistry Class 8 ICSE Solutions – Chemical Reactions

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Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 6 Chemical Reactions

Exercise – I

Question 1.
(a) Define a chemical reaction.
(b) What happens during a chemical reaction?
(c) What do you understand by a chemical bond?
Answer:
(a) Any chemical change in a matter which involves transformation into one or more substances with entirely different properties is called a chemical reaction.
(b) A chemical reaction involves breaking of chemical bonds between the atoms or groups of atoms of reacting substances and rearrangement of atoms making new bonds to form new substances.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 1
(c) A chemical bond is the attractive force that holds the atoms of a molecule together, in a compound.

Question 2.
Give one example each of which illustrates the following characteristics of a chemical reaction:
(a) evolution of a gas
(b) change of colour
(c) change in state
Answer:
(a) When Zinc reacts with dil. sulphuric acid. Hydrogen gas is evolved, with an effervescence
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 2

(b) When blue coloured copper sulphate reacts with hydrogen sulphide gas, a black coloured substance copper sulphide is formed.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 3

(c) The reaction between hydrogen sulphide and chlorine (both gases) produces sulphur (solid) and hydrogen chloride (gas).
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 4

Question 3.
How do the following help in bringing about a chemical change?
(a) pressure (b) light
(c) catalyst (d) heat.
Answer:
(a) Some chemical reactions take place when reactants are subjected to high pressure.
e.g: Nitrogen and hydrogen when subjected to high pressure produce ammonia gas.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 5

(b) Some chemical reactions can take place in the presence of light. Ex. Photosynthesis.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 6

(c) A catalyst can either increases or decreases the rate of a chemical reaction and some chemical reactions need a catalyst to change the rate of the reaction, in case it is too slow or too fast.

  1. Positive catalyst: When a catalyst increases the rate of reaction finely divided iron is used as a positive catalyst in the manufacturing of ammonia from hydrogen and nitrogen.
    Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 7
  2. Negative Catalyst: When a catalyst decreases the rate of reaction.
    Ex. Phosphoric acid act as a negative catalyst to decrease the rate of the decomposition of hydrogen peroxide.

(d) Some chemical reactions take place only in the presence of heat.
e.g. When lead nitrate is heated, it breaks into lead monoxide, nitrogen dioxide, and oxygen.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 8

Question 4.
(a) Define catalyst.
(b) What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
(c) Name three biochemical catalysts found in the human body.
Answer:
(a) Catalyst: A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change during the reaction.

(b) (i) Positive catalyst: When a catalyst increases the rate of chemical reaction, it is called a positive catalyst.
e.g. when potassium chlorate heated to 700°C decomposes to evolve oxygen gas, when MnO2 has added the decomposition takes place at 300°C
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 9
(ii) Negative catalyst: When a catalyst decreases the rate of chemical reaction it is called a negative catalyst.
Example. Phosphoric acid acts as a negative catalyst to decrease the rate of the decomposition of hydrogen peroxide. Alcohol too acts as a negative catalyst in certain chemical reactions.

(c) Biochemical catalysts found in the human body:

  1. Pepsin
  2. Trypsin
  3. lipase.

Question 5.
What do you observe when
(a) dilute sulphuric acid is added to granulated zinc?
(b) a few pieces of iron are dropped in a blue solution of copper sulphate?
(c) silver nitrate is added to a solution of sodium chloride?
(d) ferrous sulphate solution is added to an aqueous solution of sodium hydroxide.
(e) solid lead nitrate is heated?
(f) when dilute sulphuric acid is added to barium chloride solution?
Answer:
(a) When Zinc reacts with dilute sulphuric acid, hydrogen gas is evolved with effervescence.
Zn + dil. H2SO4 → Zn SO4 + H2.

(b) When a few pieces of iron are dropped into a blue coloured copper sulphate solution, the blue colour of the solution fades and eventually turns green.

(c) When a solution of silver nitrate is added to a solution of sodium chloride, white insoluble ppt. of silver chloride is formed.
AgNO3 (aq) + NaCl (aq) → AgCl (ppt) + NaNO3 (aq)

(d) When ferrous sulphate solution is added to sodium hydroxide solution, a dirty green ppt. of ferrous hydroxide is formed.
FeSO4 (aq) + 2NaOH (aq) → Fe(OH)2 ↓ + Na2SO4(aq)

(e) When solid lead nitrate is heated, it decomposes to produce light yellow solid lead monoxide, reddish-brown nitrogen dioxide gas and colourless oxygen gas.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 10

(f) When few drops of dilute sulphuric acid is added to barium chloride solution, a white precipitate of barium sulphate is formed.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 11

Question 6.
Complete and balance the following chemical equations:
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 12
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 13
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 14

Exercise – II

Question 1.
1. Fill in the blanks.
(a) A reaction in which two or more substances combine to form a single substance is called a combination reaction.
(b) A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
(c) The formation of gas bubbles in a liquid during a reaction is called effervescence
(d) The reaction between an acid and a base is called a neutralization reaction.
(e) Soluble bases are called alkalis.
(f) The chemical change involving iron and hydrochloric acid illustrates a displacement reaction.
(g) In the type of reaction called double decomposition reaction, ions two compounds exchange their positive and negative radicals ions respectively.
(h) A catalyst either increases or decreases the rate of a chemical change but itself remains unchanged at the end of the reaction.
(i) The chemical reaction between hydrogen and chlorine is a combination reaction
(j) When a piece of copper is added to silver nitrate solution, it turns blue in colour.

Question 2.
Classify the following reactions as a combination, decomposition, displacement, precipitation, and neutralization. Also, balance the equations.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 15
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 16
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 18

Question 3.
Define:
(a) precipitation (b) neutralization (c) catalyst
Answer:
(a) Precipitation: A chemical reaction in which two compounds in their aqueous state react to form an insoluble salt as one of the product.
Acid + Base → Salt + Water
Example.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 19

(b) Neutralization: A chemical reaction in which a base or an alkali reacts, with an acid to produce a salt and water only.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 20

(c) Catalyst: A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 21
here iron act as a catalyst and increases the rate of a chemical reaction.

Question 4.
Explain the following types of chemical reactions giving two examples for each of them.
(a) combination reaction
(b) decomposition reaction
(c) displacement reaction
(d) double decomposition reaction
Answer:
(a) Combination reaction: A reaction in which two or more substances combine to form a single substance is called a combination reaction.
A + B → AB
e.g (i) When iron and sulphur are heated together, they combine to form iron sulphide.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 22
(ii) When carbon bums in oxygen to form a gaseous compound called carbon dioxide.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 23
(b) Decomposition reaction: A reaction in which a compound breaks up due to the application of heat into two or more simple substances is called a decomposition reaction.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 24
e.g. (i) Mercuric oxide when heated, decomposes to form two elements mercury and oxygen
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 25
(ii) CaCO3 when heated decomposes to calcium oxide and carbon dioxide.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 26

(c) Displacement reaction: A reaction in which a more active element displaces a less active element from a compound is called a displacement reaction.
AB + C → CB + A
e.g. (i) Zinc, displaces copper from copper sulphate solution.
Zn + CuSO4 (aq) → ZnSO4 (aq) + Cu
(ii) Iron piece when added to copper sulphate solution, copper is displaced.
Fe + CuSO4 → FeSO4 + Cu.

(d) Double decomposition reaction: A chemical reaction in which two compounds in their aqueous state exchange their ions to form new compounds is called a double decomposition reaction.
AB + CD → CB + AD
e.g. (i) AgNO3 + HCl  AgCl + HNO3(aq)
(ii) NaOH (aq) + HCl (aq)  NaCl (aq) + H2O.

Question 5.
Write the missing reactants and products and balance the equations.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 27
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 28

Question 6.
How will you obtain it?
(a) Magnesium oxide from magnesium.
(b) Silver chloride from silver nitrate.
(c) Nitrogen dioxide from lead nitrate.
(d) Zinc chloride from zinc.
(e) Ammonia from nitrogen.
Also, give balanced equations for the reactions
Answer:
(a) Magnesium when burnt in air (oxygen) Magnesium oxide is formed
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 29

(b) When silver nitrate solution reacts with sodium chloride, silver chloride is formed.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 30

(c) Lead nitrate when heated nitrogen oxide is obtained
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 31

(d) Zinc when reacts with hydrochloric acid zinc chloride and hydrogen (g) is formed.
Zn + 2HCl → ZnCl2 + H2

(e) Nitrogen when reacts with hydrogen at 450°C and under 200 atm, ammonia is formed.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 32

Question 7.
What do you observe when
(a) Iron nail is kept in copper sulphate solution for some time.
(b) Phenolphthalein is added to sodium hydroxide solution.
(c) Blue litmus paper is dipped in dilute hydrochloric acid.
(d) Lead nitrate is heated.
(e) Magnesium ribbon is burnt in oxygen.
(f) Ammonia is brought in contact with hydrogen chloride. gas.
Answer:
(a) A brown layer of copper gets deposited on an iron nail. This is due to a chemical reaction.
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
(b) Solution turns pink.
(c) Blue litmus turns red in an acid solution.
(d) The pale yellow solid is lead monoxide, the reddish-brown gas is nitrogen dioxide and the colourless gas is oxygen.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 33
(e) Magnesium ribbon bums with a dazzling white light and produces a white powder which is magnesium oxide.
The reaction can be represented as
2Mg + O2 → 2MgO (white powder)
(f) Ammonia and hydrogen chloride, both compounds, combine to form a compound, ammonium chloride.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 34

Question 8.
Give reason:
(a) A person suffering from acidity is advised to take an antacid.
(b) Acidic soil is treated with quick lime.
(c) Wasp sting is treated with vinegar.
Answer:
(a) An antacid neutralizes stomach acidity.
(b) If the soil is acidic it can be treated with a base like quick lime, to make it neutral.
(c) Wasp stings are alkaline and can be neutralized by vinegar which is a weak acid.

Question 9.
What is meant by the metal reactivity series? State its importance, (any two points).
Answer:
A list in which the metals are arranged in the decreasing order of their chemical reactivity is called the metal reactivity series.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 35
Special features of the activity series:

  1. The ease with which a metal in solution loses an electron(s) and forms a positive ion decreases down the series, i.e. from potassium to gold.
  2. Hydrogen is included in the activity series because, as metals do, it too loses an electron and becomes positively charged (H+) in most chemical reactions.
  3. The series facilitates the comparative study of metals in terms of the degree of their reactivity.
  4. The compounds of the metals (oxides, carbonates, nitrates and hydroxides) too can be easily compared.

Question 10.
What are oxides? Give two examples of each of the following oxides.
(a) Basic oxide (b) Acidic oxide
(c) Amphoteric oxide (d) Neutral oxide
Answer:
An oxide is a compound that essentially contains oxygen in its molecule, chemically combined with a metal or a non-metal.
Selina Concise Chemistry Class 8 ICSE Solutions - Chemical Reactions 36

Question 11.
Define exothermic and endothermic reactions. Give two examples of each.
Answer:
Exothermic reactions: The chemical reaction in which heat is given out is called exothermic reactions. It causes rise in temperature. .
e.g. (i) When carbon bums in oxygen to form carbon dioxide, a lot of heat is produced.
C + O2 → CO2 + heat.
When water is added to quicklime a lot of heat is produced which boils the water.
CaO + H2O → Ca (OH)2 + Heat.

Endothermic reaction: A chemical reaction in which heat is absorbed is called endothermic reaction. It causes fall in temperature.
e.g. (i) When nitrogen and oxygen together are heated to a temperature of about 3000°C, nitric oxide gas is formed.
N2 + O2 + heat → 2NO (g)
(ii) Decomposition of calcium carbonate into carbon dioxide and calcium oxide when heated to a 1000°C.
CaCO3 + Heat → CaO (s) + CO2 (g)

Question 12.
State the effect of:
(a) an endothermic reaction
(b) an exothermic reaction on the surroundings.
Answer:
(a) Carbon dioxide present in the atmosphere is trapped by infrared radiations, gives rise to temperature which is exothermic reaction.
(b) The melting of glaciers by global warming.

Question 13.
What do you observe when
(a) an acid is added to a basic solution.
(b) ammonium chloride is dissolved in water.
Answer:
(a) A chemical reaction in which a base or an alkali reacts with an acid to produce a salt and water.
Acid + Base → Salt + Water
(b) Dissolution of ammonium chloride in water is an endothemic reaction in which heat energy is absorbed.

Selina Concise Chemistry Class 8 ICSE Solutions – Matter

Selina Concise Chemistry Class 8 ICSE Solutions – Matter

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ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 1 Matter. You can download the Selina Concise Chemistry ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Chemistry for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 1 Matter

Exercise

Question 1.
Define:
(a) matter
(b) intermolecular force of attraction.
Answer:
(a) Matter is anything which has mass, occupies space and can be percieved by our senses.
Example: Air, Book.
(b) The molecules of matter are always in motion and attract each other with a force called intermolecular force of attraction due to which they are held together.

Question 2.
What are the three states of matter ? Define each of them with two examples.
Answer:
The three states of matter are:
solids, liquids and gases

  • Solids — A solid has a definite shape and definite volume.
    Example – wood, stone, iron, ice etc.
  • Liquid — A liquid has a definite volume but not definite shape.
    Example — water, juice, milk, oil, etc.
  • Gases — A gas neither has definite shape nor a definite volume.
    Example – air, hydrogen, oxygen, watervapour etc.

Question 3.
Define interconversion of states of matter. What are the two factors responsible for the change of states of matter?
Answer:
The process by which matter changes from one state to another and back to original state, without any change in its chemical composition is called interconversion state of matter.
Two factors responsible for change of state of matter are: change in
(i) Temperature (ii) Pressure

Question 4.
State the main postulates of kinetic theory of matter.
Answer:
The main postulates of the theory are:

  1. Matter is composed of very small particles called atoms and molecules.
  2. The constituent particles of a kind of matter are identical in all respects.
  3. These particles have space or gaps between them which is known as interparticular or intermolecular space.
  4. There exists a force of attraction between the particles of matter which holds them together. This force of attraction is known as interparticular or intermolecular force of attraction.
  5. Particles of matter are always in a state of random motion and possess kinetic energy, which increases with increase in temperature and vice-versa.

Question 5.
What happens to water if
(a) it is kept in a deep freezer
(b) it is heated
Explain the phenomenon of change of state of water.
Answer:
(a) When water is kept in a deep freezer, it gets cooled and change into ice at 0°C ice.
Selina Concise Chemistry Class 8 ICSE Solutions - Matter 1
(b) Water on heating changes into steam at 100°C
Selina Concise Chemistry Class 8 ICSE Solutions - Matter 2

Phenomenon of change of state of water:
Water is a liquid under ordinary conditions but, when it is kept in a deep freezer, it changes into ice at 0°C and when ice is kept at room temperature again changes back into liquid water.
Similarly, water on heating change into steam at 100°C, which on cooling changes back into liquid water. But there is no change in the chemical composition of water. When its state changes from liquid to solid or liquid to gaseous state.
Selina Concise Chemistry Class 8 ICSE Solutions - Matter 3

Question 6.
(a) State the law of conversation of mass.
(b) What do you observe when barium chloride solution is mixed with sodium sulphate solution?
Answer:
(a) “Matter can neither be created nor be destroyed in a chemical reaction”. However, it may change from one form to another in the process.
It can also be stated as, “In a chemical reaction, the total mass of the reactants is equal to the total mass of the products”.

(b)
Selina Concise Chemistry Class 8 ICSE Solutions - Matter 4
We will observe that a white insoluble solid (precipitate) of barium sulphate is formed along with a solution of sodium chloride. Wait for ten minutes to complete the reaction and the solid formed to settle down.
Weigh the content again and note the reading.
We will observe that,
total mass of the apparatus + reactants = total mass of apparatus + products
Hence the law of conservation of mass is verified.

Question 7.
Give reasons:
(a) A gas can fill the whole vessel in which it is enclosed.
(b) Solids cannot be compressed.
(c) Liquids can flow.
(d) When magnesium is burnt in air, there is an increase in mass after the reaction.
Answer:
(a) Because, in gases, the molecules are free to move.
They are not stuck to each other and the intermolecular force of attraction is least in the gases. So the gas almost filled the whole vessel in which it is enclosed.

(b) In solids, particles are closely packed. There is a strong force of attraction and the intermolecular space is almost zero. Therefore the molecules are not free to move, which makes them hard and rigid. So solids can not be compressed.

(c) In liquids intermolecular force is weaker because the particles are not closely packed and hence there is large intermolecular space. So molecules in a liquids can move randomely and hence liquids can flow easily.

(d) When magnesium ribbon is burnt in air, a white solid, magnesium oxide is formed. The mass of magnesium oxide is more than the mass of magnesium. This is because mass of oxygen used is not taken. If that is considered, the total mass of the reactants and the products is found to be almost equal.
Selina Concise Chemistry Class 8 ICSE Solutions - Matter 5

Question 8.
Fill in the blanks:

(a) The change of a solid into a liquid is called melting or fusion.
(b) The process in which a solid directly changes into a gas is called sublimation.
(c) The change of water vapour into water is called condensation.
(d) The temperature at which a liquid starts changing into its vapour state is evaporation or vaporisation.

Question 9.
Give two examples for each of the following:
(a) The substances which sublime.
(b) The substances which do not change their state on heating.
Answer:
(a) Camphor, iodine, naphthalene, ammonium chloride, dry ice (solid carbon dioxide), etc.
(b) Gases do not change their state on heating.
Example: O2.

Question 10.
Define:
(a) Diffusion.
(b) Brownian motion.
Answer:
(a) Diffusion: The intermixing of two or more substances due to the motion of their particles in order to get a uniform mixture is called ‘diffusion’.
(b) Brownian motion: The haphazard, random motion of suspended particles on the surface of a liquid or in air is called ‘Brownian motion’.

Question 11.
When sodium chloride is added to a definite volume of water and stirred well, a solution is formed, but there is no increase in the level of water. Why?
Answer:
This is because there is some space between the particles of water in which the salt particles get accomodated when dissolved.

Question 12.
What do you observe when a gas jar which appears empty is inverted over a gas jar containing Bromine vapours? Name the phenomenon.
Answer:
When a gas jar full of bromine vapours (reddish brown) is inverted over a gas jar containing air over it. It is observed that after sometime, the reddish brown vapours of bromine also spread out into the upper jar. This mixing is called diffusion. The rate of diffusion is the fastest in gases and the slowest in solids. It increases with an increase in temperature.

Question 13.
Why can a piece of chalk be broken easily into smaller pieces while a coal piece cannot be broken easily?
Answer:
The particles of matter have force acting between them. This force keeps the particles together. The strength of this force of attraction is lesser in chalk, hence it could be broken easily into smaller pieces.
But the strength of inter-molecular force of attraction is very strong in coal, therefore it is not possible to break them into small pieces.

Selina Concise Physics Class 8 ICSE Solutions – Light Energy

Selina Concise Physics Class 8 ICSE Solutions – Light Energy

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ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Physics Chapter 5 Light Energy. You can download the Selina Concise Physics ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Physics for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Physics Chapter 5 Light Energy

  • Light is a form of energy which produces in us the sensation of sight i.e. we can see objects only when light falls on them and then reflected into our eye.
  •  Velocity of light in air or in vacuum is 300000 km per second.
    Or
    3 x 10ms-1
  • As light passes into different mediums its speed changes and depends upon the density of medium i.e. it decreases with increase in density i.e. it is 2.25 × 108 m/s in water and 2 x 108 ms-1 in glass as water is
    denser than air ( \(_{ w }^{ a }{ \mu }\) = 1.33 ) and glass is still optically denser than water
    ( \(_{ g }^{ a }{ \mu }\) =1.5 ) i.e. slower in water and still slower in glass.
  • Light travels in a straight line.
  • As light travels from one transparent medium to other transparent medium and falls oblique at another medium, its path changes and this change in path is called REFRACTION OF LIGHT.
  •  When ray of light travels from RARER (less-denser) to DENSER medium, it bends TOWARD the normal AND when it travels from a DENSER to a RARER medium it bends away from NORMAL
  •  ANGLE of INCIDENCE : “The angle which incident ray makes with normal”. “∠i”
  •  ANGLE OF REFRACTION: “The angle which refracted ray makes with normal” “ ∠r ”
    ∠i is not equal to ∠r
  •  LAWS OF REFRACTION or SNELL’S LAWS OF REFRACTION:
    (i) Incident ray, normal at the point of incidence and Refracted ray all lie in the same plane.
    (ii) Ratio of sine of angle of incidence to the sine of angle of refraction is constant.
  • Selina Concise Physics Class 8 ICSE Solutions Chapter 5 Light Energy 1
  •  EFFECTS OF REFRACTION :
    (i) A coin placed in water appears to be raised.
    (ii) Swimming pool seen from above appears SHADOW.
    (iii) A pencil in water appears to be bent.
    (iv) MIRAGE in desert, EARLY Sunrise, LATE SUN set are all due to REFRACTION of light.
  • White light is a band of seven colours-VIBGYOR. Speed of all colours of the white light in AIR or VACUUM is same, but different different transparent mediums.
  •  In glass or water Speed of VIOLET colour is MINIMUM and speed of RED light is MAXIMUM
  • Refractive index of medium is minimum for VIOLET light and R.I. of medium is maximum for red light.
  • DISPERSION: “The splitting (breaking) of white light into seven colours is called DISPERSION OF LIGHT.
  •  CAUSE OF DISPERSION: Speed of different colours is different in glass or water and different colours get separated from each other on refraction at second surface of glass prism.

Test yourself

A. Objective Questions

1. Write true or false for each statement

(a) Water is optically denser than glass.
Answer. False.
Water is optically denser than air.

(b) A ray of light when passes from glass to air, bends towards the normal.
Answer. False.

(c) The speed of light is more in glass than in water.
Answer. False.

(d) The depth of a pond when seen from above appears to be less.
Answer. True.

(e) Light travels at a lower speed in water than in air.
Answer. True.

(f) Light travels in the same straight line path while passing through different media.
Answer. False.

(g) The angle formed between the normal and the refracted ray is known as the angle of incidence.
Answer. False.

(h) At the point of incidence, a line drawn at right angles to the surface, separating the two media, is called the normal.
Answer. True.

(i) Image is formed by a mirror due to refraction of light.
Answer. False.

(j) Rays of light incident parallel to the principal axis pass through the focus after reflection from a concave mirror.
Answer. True.

(k) A convex mirror is used as a shaving mirror.
Answer. False.

(l) The focal length of a convex mirror is equal to its radius of curvature.
Answer. False.

(m) A concave mirror converges the light-rays, but a convex mirror diverges them.
Answer. True.

(n) A virtual image formed by a spherical mirror is always erect and situated behind the mirror.
Answer. True.

2. Fill in the blanks

(a) Water is optically denser than air.
(b) Air is optically rarer than glass.
(c) When a ray of light travels from water to air, it bends away from the normal.
(d) When a ray of light travels from air to glass, it bends towards the normal.
(e) When white light passes through a prism, it disperses
(f) The splitting of white light into its constituent colours is called dispersion.
(g) A concave mirror is obtained on silvering the outer surface of a part of a hollow glass sphere.
(h) Radius of curvature of a spherical mirror is two times its focal length.
(i) The angle of incidence for a ray of light passing through the centre of curvature of a spherical mirror is
(j) A convex mirror always forms a virtual image.
(k) A concave mirror forms a virtual image for an object placed between pole and focus.

 

3. Match the following
Selina Concise Physics Class 8 ICSE Solutions Chapter 5 Light Energy 2

4. Select the correct alternative

(a) The speed of light in air or vacuum is

  1. 3 × 10M s-1
  2.  2.25 × 108 m s-1
  3.  332 ms-1
  4.  2.0 × 108 ms-1

(b) A ray of light moving from an optically rarer to a denser medium

  1.  bends away from the normal
  2.  bends towards the normal
  3.  remains undeviated
  4.  none of the above

(c) The angle between the normal and refracted ray is called

  1.  angle of deviation
  2.  angle of incidence
  3.  angle of refraction
  4.  angle of emergence.

(d) The property of splitting of white light into its seven constituent colours is known as

  1.  rectilinear propagation
  2.  refraction
  3.  reflection
  4.  dispersion

(e) The seven colours in the spectrum of sunlight in order, are represented as :

  1.  VIBGYOR
  2.  VIGYBOR
  3.  BIVGYOR
  4.  RYOBIVG

(f) A ray of light passing through centre of curvature of a spherical mirror, after reflection

  1. passes through the focus
  2.  passes through the pole
  3.  becomes parallel to the principal axis
  4.  retraces its own path.

(g) If the radius of curvature of a concave mirror is 20 cm, its focal length is:

  1.  10 cm
  2.  20 cm
  3.  40 cm
  4.  80 cm

(h) The image formed by a convex mirror is

  1.  erect and diminished
  2.  erect and enlarged
  3.  inverted and diminished
  4.  inverted and enlarged.

(i) The image formed by a concave mirror is of the same size as the object, if the object is placed

  1. at the focus
  2. between the pole and focus
  3.  between the focus and centre of curvature
  4.  at the centre of curvature.

(j) A convex mirror is used

  1.  as a shaving mirror
  2.  as a head mirror by a dentist
  3.  as a rear view mirror by a driver
  4.  as a reflector in torch.

Selina Concise Chemistry Class 8 ICSE Solutions – Elements, Compounds and Mixtures

Selina Concise Chemistry Class 8 ICSE Solutions – Elements, Compounds and Mixtures

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ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 3 Elements, Compounds and Mixtures. You can download the Selina Concise Chemistry ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Chemistry for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 3 Elements, Compounds and Mixtures

Exercise 3(A)

Question 1.
Define: (a) Elements (b) Compounds
Answer:
(a) Elements: Element is a substance which cannot be broken further into simpler substances and has a definite set of properties. Elements are made up of only one kind of atoms.
(b) Compounds: Compounds are pure substances composed of two or more elements in definite proportion by mass and has properties, entirely different from those of its constituents elements.
Compound, are made up of different types of atoms combined chemically.

Question 2.
Give two examples for each of the following:
(a) Metals (b) Non-metals
(c) Metalloids (d) Inert gases
Answer:
(a) Metals: Iron, silver, gold.
(b) Non-metals: Carbon, sulphur, oxygen.
(c) Metalloids: Antimony, silicon, boron.
(d) Inert gases: Helium, argon, neon.

Question 3.
Differentiate between:
(a) Pure and impure substances
(b) Homogenous and heterogenous substances
Answer:
(a) Pure substances —

  1. Pure substances have definite composition and definite physical and chemical properties.
  2. They are all homogeneous i.e. their composition is uniform throughout the bulk.
  3. Examples: Elements and compounds.

Impure substances —

  1. Impure substances are made up of two or more pure substances mixed together in any proportion.
  2. They may be homogeneous or hetergeneous i.e. their composition is not uniform throughout the bulk.
  3. They are all mixtures.
    Examples: air, sea water, petroleum, a solution of sugar in water are all impure substances.

(b) Homogeneous mixture — is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture.
Example — air, sugar water, rain water.
Heterogeneous mixture — is a mixture, where the components of the mixture are not uniform or have localized regios with different properties.
Example—Cereal in milk, vegetable soup.

Question 4.
Write the chemical name of the following and also give their molecular formulae:
(a) Baking soda (b) Vinegar
(c) Marble (d) Sand
Answer:
(a) Sodium bicarbonate (Baking soda) — NaHCO3
(b) Acetic acid (Vinegar) — CH3COOH
(c) Calcium carbonate (Marble) — CaCO3
(d) Silicon dioxide (Sand) — SiO2

Question 5.
Name:
(a) a soft metal
(b) a metal which is brittle
(c) a non-metal which is lustrous
(d) a liquid metal
(e) a metal which is a poor conductor of electricity.
(f) a non-metal which is a good conductor of electricity.
(g) a liquid non-metal
(h) the hardest naturally occurring substance
(i) an inert gas
Answer:
(a) Gold
(b) Zinc
(c) Iodine
(d) Mercury
(e) Tungsten
(f) Graphite
(g) Bromine
(h) Diamond
(i) Neon, helium

Question 6.
How is sodium chloride different from its constituent elements ?
Answer:
The properties of sodium chloride are completely different from those of sodium and chlorine. Sodium is a soft, highly reactive metal. Chlorine is a poisonous non-metallic gas while sodium chloride is a very useful non poisonous compound which is added to our food to get minerals and also to add taste to it.

Question 7.
Why is iron sulphide a compound ?
Answer:
Iron sulphide is a compound which can be broken into the elements iron and sulphur they both have different properties. The properties of compound are entirely different from there of its constituents elements.

Exercise 3(B)

Question 1.
Classify the following substances into compounds and mixtures:
Answer:
Carbon dioxide, air, water, milk, common, salt, blood, fruit juice, iron sulphide.
Carbon dioxide — (Compound)
air — (Mixture)
water — (Compound)
milk — (Mixture)
common salt — (Compound)
blood — (Mixture)
fruit juice — (Mixture)
iron sulphide — (Compound)

Question 2.
Give one example for each of the following types of mixtures
(a) solid-solid homogenous mixture
(b) solid-liquid heterogenous mixture
(c) misicible liquids
(d) liquid-gas homogenous mixture
Answer:
(a) Solid-solid homogenous mixture — Alloys of metals e.g. brass, bronze stainless steel etc.
(b) Solid-liquid heterogenous mixture — Sand and water, mud and water, sugar and oil.
(c) Misicible liquids — water and ethanol.
(d) Liquid-gas homogenous mixture — Air

Question 3.
Suggest a suitable technique to separate the constituents of the following mixtures. Also give the reason for selecting the particular method.
(a) Salt from sea water
(b) Ammonium chloride from sand
(c) Chalk powder from water
(d) Iron from sulphur
(e) Water and alcohol
(f) Sodium chloride and potassium nitrate
(g) Calcium carbonate and sodium chloride
Answer:

(a) The technique used to separate the salt from seawater is Evaporation.
Reason – Because this method is used to separate the components of the homogeneous solid-liquid mixture. In this method, sea water is collected in a shallow bed and allowed to evaporate in the sun. When all the water is evaporated, salt is left behind. By this method, we only get solid and liquid is evaporated in its vapour form.

(b) Technique used to separate Ammonium chloride from sand is sublimation.
Because this method is used for solid mixtures in which one of the components can sublime on heating. In this method, Ammonium chloride changes into vapours on heating and salt is left behind.

(c) Technique used to separate chalk powder from water is filtration.
Reason – Because this process is used to separate the components of a heterogeneous solid-liquid mixture in which solids are lights and insoluble in liquids. Substances used as filters are sand filter paper at C. These filters allows the liquid to pass through them, but not solids.

(d) Technique to separate iron from sulpher is magnetic separation.
Because, this method is used when one of the component of mixture is Iron. Iron gets attracted towards the magnet and hence get separated.

(e) Technique used to separate water and Alcohol is Fractional Distillation.
Because in this method, the vapours of water is left behind in the original vessel as the alcohol boils at lower temperature than water. Thus these two liquids can be separated.

(f) Technique used is Fractional-crystallisation.
Because: This method is used when solubility of solid components of mixture and different in the same solvent. Here, sodium chloride and potassium nitrate. Both are soluble in water but solubility of potassium nitrate is more.

(g) Technique used is Solvent Extraction Method: Because, by this method, salts get dissolve in water while calcium carbonate being insoluble in water settles down in the container. And hence get separated about.

Question 4.
(a) Define mixture.
(b) Why is it necessary to separate the constituents of a mixture.
(c) State four differences between compounds and mixtures.
Answer:
(a) “Mixtures can be defined as. a kind of matter which is formed by mixing two or more pure substances (elements and compounds) in any proportion, such that they do not undergo any chemical change and retain their individual properties. Therefore they are impure substances.

(b) Because: The mixtures contain unwanted substances which may be harmful and may degrade the properties of mixtures. So we, need to separated them and extract useful substances.
This is necessary because
(i) It removes unwanted and harmful substances
(ii) to obtain pure and useful substances them.
Example: Sea water is rich in common salt which is an important ingredient of our food to add taste and nutrients. But sea water, cannot be directly used to get the salt.
Hence, it is necessary to separate both.

(c) Compound

  1. A compound is formed from its constituent elements as a result of chemical reaction.
  2. A compound is always homogeneous in nature.
  3. In a compound the elements are present in a fixed ratio by weight.
  4. The components of a compound can’t be separated by physical methods but can be separated by chemical methods only.
  5. The properties of a compound are different from those of its elements.
  6. The formation of a compound from its elements is accompanied by energy changes.

Mixture

  1. A mixture is obtained form its (elements, compounds) components as a result of physical change.
  2. The mixtures can be homogeneous or heterogeneous.
  3. In a mixture the components can be present in any ratio.
  4. The components of a mixture can be separated by physical methods only.
  5. The properties of a mixture lie between those of-its components.
  6. The formation of a mixture from its constituents is not accompanied by energy changes.

Question 5.
(a) What is chromatography ? For which type of mixture is it used ?
(b) What are the advantages of chromatography.
Answer:
(a) This is one of the latest techniques to separate the coloured components of a mixture when all the components are very similar in their properties. Example: Components of ink are separated by this method. Ink is a mixture of different dyes, which are separated by chromatography because some of the dyes are less soluble and some are more soluble in a solvent.

(b)

  1. A very small quantity of the substance can be separated.
  2. Components with very similar physical and chemical properties can be separated.
  3. It identifies the different constitutes of a mixture.
  4. It also helps in quantitive estimation of components of a mixture.

6. Choose the most appropriate answer from the options given below:

(a) a mixture of sand and ammonium chloride can be separated by

  1. filtration
  2. distillation
  3. sublimation
  4. crystallisation

(b) A pair of metalloids are

  1. Na and Mg
  2. B and Si
  3. C and P
  4. HeandAr

(c) Which of the following property is not shown by compounds?

  1. They are heterogeneous.
  2. They are homogeneous.
  3. They have definite molecular formulae.
  4. They have fixed melting and boiling points.

(d) A solvent of Iodine is

  1. Water
  2. Kerosene oil
  3. Alcohol
  4. Petrol

(e) Which of the gas is highly soluble in water ?

  1. Ammonia
  2. Nitrogen
  3. Carbon monoxide
  4. Oxygen

Selina Concise Chemistry Class 8 ICSE Solutions – Carbon and Its Compounds

Selina Concise Chemistry Class 8 ICSE Solutions – Carbon and Its Compounds

ICSE Solutions  Selina ICSE Solutions  ML Aggarwal Solutions

ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 9 Carbon and Its Compounds. You can download the Selina Concise Chemistry ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Chemistry for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 9 Carbon and Its Compounds

Points to Remember:

  1. Carbon occurs in the earth’s crust in the free as well as in the combined state.
  2. In the free state, it occurs as coal, diamond and graphite.
  3. In the combined state, carbon occurs in atmosphere (CO2) natural gas, food nutrients and carbonates.
  4. Diamond is the hardest naturally occuring substance known.
  5. Fullerenes are discovered only recently.

Exercise – I

Question 1.
Fill in the blanks.
(a) Carbon is present in both living and non-living things.
(b) The tendency of an element to exist in two or more forms but in the same physical state is called Allotropy.
(c) Crystalline and non-crystalline are the two major crystalline allotropes of carbon.
(d) Diamond is the hardest substance that occurs naturally.
(e) The name ‘carbon’ is derived from the Latin word carbo.

Question 2.
Choose the correct alternative.

(a) In a combined state, carbon occurs as
(i) coal
(ii) diamond
(iii) graphite
(iv) petroleum

(b) A crystalline form of carbon is
(i) lampblack
(ii) gas carbon
(iii) sugar
(iv) fullerene

(c) Graphite is not found in
(i) Bihar
(ii) Maharashtra
(iii) Orissa
(iv) Rajasthan

(d) Diamond is used for
(i) making the electrodes of electric furnaces.
(ii) making crucible for melting metals.
(iii) cutting and drilling rocks and glass.
(iv) making carbon brushes for electric motors.

(e) Carbon forms innumerable compounds because
(i) it has four electrons in its outermost shell.
(ii) it behaves as metal as well as non-metal.
(iii) carbon atoms can form long chains.
(iv) it combines with other elements to form covalent compounds.

Question 3.
Write ‘true’ or ‘false’ against the following statements.

(a) Carbon constitutes 0.03% of the earth’s crust. – True
(b) Graphite is the purest form of carbon. – False
(c) Coloured diamonds are costlier than colourless and transparent diamonds. – False
(d) Graphite has layers of hexagonal carbon bondings. – True
(e) Diamond is insoluble in all solvents. – True.

Question 4.
Define the following terms:

(a) Allotropy (b) Carat
(c) Crystal (d) Catenation
Answer:
(a) Allotropy: Allotropy is defined as the phenomenon due to which an element exists in two or more forms in the same physical state with identical chemical properties but with different physical properties.

(b) Carat – The weight of diamond is expressed in carats [ 1 carat = 0.2 g]

(c) Crystal – A crystal is a homogeneous solid in which particles (atoms, molecules, or ions) are arranged in the definite pattern due to which they have a definite geometrical shape with plane surfaces e.g. sugar and sodium chloride.

(d) Catenation – A large number of organic compounds is due to the ability of carbon atoms to form long chains with other carbon atoms through the sharing of electrons. This unique property of carbon is known as catenation.
Selina Concise Chemistry Class 8 ICSE Solutions - Water 6

Question 5.
State the terms:

(a) Substances whose atoms or molecules are arranged in a definite pattern. – Crystals.
(b) Different forms of an element found in the same physical state. – Allotropy.
(c) The property by which atoms of an element link together to form long chain or ring compounds. – Catenation

Question 6.
Name the following:

(a) The hardest naturally occurring substance. – Diamond.
(b) A greyish black non-metal that is a good conductor of electricity. – Graphite.
(c) The third crystalline form of carbon. – Fullerenes.

Question 7.
Answer the following questions:

(a) Why is graphite a good conductor of electricity but not diamond?
(b) Why is diamond very hard?
(c) What are fullerenes? Name the most common fullerenes.
(d) What impurity is present in black diamond?
(e) Explain the softness of graphite with reference to its structure.
Answer:
(a) In a graphite molecule, one valence electron of each carbon atom remains free, Thus making graphite a good conductor of electricity. Whereas in diamond, they have no free mobile electron. Thats why diamond are bad conductor electricity.

(b) A diamond is a giant molecule. The number of valence electrons in carbon atom is four. As such each carbon atom is linked with four neighboring carbon atoms. Thus forming a rigid tetrahedral structure. It is the strong bonding’that makes diamond the hardest substance.

(c) Fullerenes: Fullerenes are the third crystalline form of carbon.
Though they were discovered only recently. They have.been found to exist in interstellar dust as well as in the geological formations of the earth.
Common fullerenes are C – 32, C – 50, C – 70 and C – 76

(d) Black diamonds have copper oxide present in them as impurity.

(e) In a graphite molecule of each carbon atoms is linked with three neighboring carbon atoms. Thus forming a hexagonal arrangement of atoms. These hexagonal grouping of carbon atoms are arranged as layers or sheets piled one the top of other. The layers are held together by weak forces such that they can slide over one another. That is why graphite is soft.

Question 8.
Give two uses of (a) graphite (b) diamond.
Answer:

(a) Uses of graphite:

  1. For making the electrodes of electric furnaces.
  2. For making crucibles for melting metals due to its high melting points.

(b) Uses of Diamond:

  1. Diamond is used in jewellery as a gem
  2. It is used for cutting and drilling rocks, glass,

Question 9.
Write three differences between graphite and diamond.
Answer:
Difference between diamond and graphite.

Diamond

  1. Pure diamond is colourless and transparent.
  2. It is the hardest naturally occurring substance.
  3. It has high density i.e. 3.5 g/cm3
  4. It is bad conduct of electricity.
  5. It bums in air at 900°C to form carbon dioxide.

Graphite

  1. Graphite is greyish black opaque and shiny.
  2. It is soft and greasy to touch.
  3. It has low density i.e. 2.39 g / cm3
  4. It is good conductor of electricity.
  5. It bums in air at 700° C to form carbon dioxide.

Exercise – II

Question 1.
Fill in the blanks:

(a) Charcoal is formed when charcoal is burnt in a limited supply of air.
(b) Coal is a amorphous form of carbon.
(c) Peat is the most inferior form of coal.
(d) Wood charcoal is a bad conductor of heat and electricity.
(e) lampblack is used in making black shoe polish.

Question 2.
Choose the correct alternative

(a) Anthracite is
(i) an inferior type of coal
(ii) a superior type of coal
(iii) a cheapest form of coal
(iv) none of above

(b) Destructive distillation of coal yields
(i) coal tar
(ii) coal gas
(iii) coke
(iv) all of the above

(c) Lamp black is
(i) an amorphous form of carbon
(ii) a crystalline form of carbon
(iii) a pure form of carbon
(iv) a cluster of carbon atoms

(d) The process by which decayed plants slowly convert into coal is called.
(i) petrification
(ii) carbonisation
(ii) carbonification
(iv) fermentation

(e) The purest form of the amorphous carbon is
(i) wood charcoal
(ii) sugar charcoal
(iii) bone charcoal
(iv) lampblack

Question 3.
Write ‘true’ or ‘false’ against the following statements:

(a) Charcoal is a good adsorbent. True
(b) Coke is obtained by destructive distillation of sugar. False
(c) Activated charcoal is a good conductor of electricity. False
(d) Wood charcoal is an important constituent of gun powder. True
(e) Coal gas is used in the preparation of artificial ferilizers. False.

Question 4.
Define the following:

(a) Carbonization
(b) Adsorption
(c) Bone black
Answer: 
(a) Carbonization: The process of the slow conversion of vegetable matter into carbon-rich substances is called carbonization.
(b) Adsorption: Adsorption is the property due to which a substance absorbs gases, liquids and solids on its surface.
(c) Bone black: The Carbon content of bone charcoal is separated by treating the latter with hydrchloride acid, which dissolves the calcium phosphate. Carbon is then filtered out of the solution and in this form it is called bone black.

Question 5.
Name the following:

(a) Substances whose atoms or molecules are not arranged in a geometrical pattern. – Amorphous
(b) The best variety of coal. – Bituminous
(c) The purest form of amorphous carbon. – Anthracite
(d) An amorphous form of carbon that contains about 98% carbon. – Anthracite
(e) Mixture of carbon monoxide and hydrogen. – Water gas.

Question 7.
Answer the following questions:

(a) What is destructive distillation? What are the products formed due to the destructive distillation of coal?
(b) Why is wood charcoal used in water filters and gas masks?
(c) How is wood charcoal made locally? What other substances are formed in the process.
(d) How many carbon atoms are there in Buckminster fullerenes?
Answer: 
(a) Destructive Distillation: When a substances is heated in the absence of air. The process is called destructive distillation.
Products formed are: Coke, Coal tar, Coal gas and ammonia solution

(b) Due to its high adsorbing capacity, wood charcoal is used as gas masks to adsorb harmful gases. Wood charcoal is porous, that is why it is used to filter water.

(c) Wood charcoal is prepared when wood is heated in a limited supply of air. Locally wood charcoal is prepared by piling logs of wood one above the other with a gap in the centre of the pile. The pile is covered with wet clay to prevent the entry of air. A few holes are left at the bottom of the pile. The wood is set on fire. After some time when fire dies out, wood charcoal is left behind. The other substances are -wood tar, pyroligneous acid and wood gas.
Selina Concise Chemistry Class 8 ICSE Solutions - Water 7

(d) 60 carbon atoms are arranged in spherical structure in Buck minster fullerences.

Question 7.
(a) Descirbe the formation of coal,
(b) Name four types of coal with percentage of carbon present in each, with uses.
Answer:
(a) Formation of coal:- The formation of coal took millions of years. Coal was formed by the bacterial decomposition of ancient vegetable matter hurried under successive layers of the earth. Under in action of high temperature and pressure, and in the abcence of air, the decayed vegetable matter converted into coal.
(b) Types of Coal:

  1. Peat: It is light brown in colour and contains only 50 – 60% carbon. It is the most inferior form of coal.
  2. Lignite: it contains more than 60% carbon. It is brown in colour and harder than peat.
  3. Bituminous: It has 90%, 80%, 70 – 75% carbon contents. Bituminous coal is the most common variety of coal and used as house hold coal.
  4. Anthracite: It is the purest variety of coal. Its carbon contents vary between 92 – 98%. It is hard, dense and black, difficultto ignite.

Uses of coal:

  1. Coal is used as both domestic and industrial fuel.
  2. It is used to prepare coke, coal gas and coal tar.

Question 9.
Name the products formed when:

(a) wood is burnt in the absence of air.
(b) bone is heated in the absence of air.
(c) diamond is burnt in air at 900°C.
(d) graphite is subjected to high pressure and 3000°C temperature.
Answer:
(a) Wood charcoal is formed when wood is burnt in limited supply of air.
(b) Bone charcaol, bone oil and organic compound pyridine.
(c) Carbon dioxide.
(d) Artificial diamond.

Question 9.
Give two uses for each of the following:

(a) coal
(b) coke
(c) wood charcoal
(d) sugar charcoal
(e) bone charcoal
(f) lampblack
Answer: 
(a) Uses of coal

  • It is used as both a domestic and an industrial fuel.
  • It is used to prepare coke, coal gas and coal tar.

(b) Uses of coke

  • Coke is used as a smokeless fuel, in smelting furnaces.
  • It is used in the manufacturing of water and producer gas.

(c) Uses of wood charcoal:

  • Wood charcoal is used as a fuel.
  • It is an important constituent of gun powder.

(d) Sugar charcoal:

  • Sugar charcoal is mostly used as a reducing agent.
  • It is used to decolourise coloured solutions.

(e) Bone charcoal:

  • It is extensively used to decolourise cane-sugar in the process of manufacturing sugar.
  • It is also used in the manufacture of large number of phosphorous compounds.

(f) Uses of lamp black:

  • It is used in making black shoe polish.
  • It is used in the manufacture of tyres and gun powder.

Question 10.
Give balanced equations for the following chemical reactions:

(a) wood charcoal and cone, nitric acid
(b) coke and steam
(c) wood charcoal and lead monoxide.
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Water 8

Exercise – III

Question 1.
(a) Name the chemicals required for the preparation of carbon dioxide in the laboratory.
(b) How will you collect the gas?
(c) Write the balanced chemical equation for the above reaction.
(d) Draw a labelled diagram for the preparation of CO2 in the laboratory.
(e) Why is sulphuric acid not used for the preparation of carbon dioxide in the laboratory?
Answer:
(a) Calcium carbonate and dilute hydrochloric acid.
(b) By upward displacement of air.
(c) CaCO3 + 2HCl → CaCl2 + H2O + CO2.
(d) Laboratory preparation of carbon dioxide
Selina Concise Chemistry Class 8 ICSE Solutions - Water 9

(e) Dilute sulphuric acid reacts with calcium carbonate. But it is not used because the calcium sulphate which is formed during the reaction is insoluble in water. It covers the marble chips and stops the reaction.
Selina Concise Chemistry Class 8 ICSE Solutions - Water 10

Question 2.
Write the balanced chemical equations for the preparation of carbon dioxide by:
(a) heating calcium carbonate.
(b) the action of acetic acid on sodium bicarbonate.
(c) the action of dilute sulphuric acid on sodium bicarbonate.
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Water 11

Question 3.
What happens when:
(a) a lit splinter is introduced into a jar containing carbon dioxide?
(b) moist blue litmus paper is placed in a jar containing carbon dioxide?
(c) carbon dioxide is passed through lime water first in small amounts and then in excess?
(d) a baking mixture containing baking powder is heated?
(e) a soda water bottle is opened?
Answer:
(a) Lit splinter extinguishes.
(b) Blue litmus paper turns red.
(c) When CO2 is passed through lime water in small amount, it turns milky, when passed in excess milkiness disappears.
(d) Carbon dioxide is formed.
(e) When the pressure is released the bottled gas escapes with a bristling effervescence that ads fizz to the drink.

Question 4.
Give reasons for the following:
(a) An excess of carbon dioxide increases the temperature of the earth.
(b) Soda acid and foam types of fire extinguisher are not used for extinguishing electrical fires.
(c) Solid carbon dioxide is used for refrigeration of food.
Answer:
(a) Excess carbon dioxide increases the temperature of the earth. Due to the rise in temperature ice in the polar regions may melt causing floods in coastal regions island.
(b) In both of these fire extinguishers, the solutions are prepared in water, which conducts electricity. As a result, an electric shock might result, which might lead to short-circuiting and another fire.
(c) Solid carbon dioxide serves as a coolant and refrigeration for preserving food articles.

Question 5.
What is a fire extinguisher? What is the substance used in the modern type of fire extinguishers? How is it an improvement over the soda acid-type and the foam-type fire extinguishers?
Answer:
Fire Extinguisher— Fire extinguishers are a device in which carbon dioxide is produced in different forms for use as the extinguishing agent. It is a modem type of fire extinguisher in which liquid carbon dioxide is stored in a steel cylinder under pressure. Soda-acid and foam types of extinguisher cannot be used for extinguishing fire as they prepared in water, which conducts electricity and there can be short-circuiting, causing another fire.

Question 6.
Explain the term ‘greenhouse effect’. How can it be both beneficial and harmful for life on earth ?
Answer:
Green house effect— The trapping of the earth’s radiated energy by carbon dioxide present in air, so as to keep the earth warm, is called ‘green house effect’.
Green house is beneficial because this principle is applied to grow plants in colder regions.
Carbon dioxide increases the temperature of atmosphere. Due to rise in temperature; ice in the polar regions may melt, causing floods. So it is harmful for life on earth.

Question 7.
What steps should be taken to balance carbon dioxide in the atmosphere ?
Answer:
As global warming will cause an unbalanced ecological system, serious efforts should be made to balance the percentage of carbon dioxide in the atmosphere. Some of these steps are:

  • Growing more trees and plants.
  • Using smokeless sources of energy like solar energy, biogas, etc.
  • Using filters in the chimneys of factories and power houses.

Question 8.
State three ways by which carbon dioxide gas is added into the atmosphere.
Answer:

  1. By planting more trees.
  2. By combustion of fuels
  3. By decay of dead animals, plants and plants products.

Exercise – IV

Question 1.
Fill in the blanks:

(a) Carbon monoxide is formed when carbon is burnt in a limited supply of air or oxygen.
(b) Carbon monoxide bums in air with a pale blue flame to form carbon dioxide.
(c) Carbon monoxide is a products of incomplete combustion.
(d) A mixture of 95% oxygen and 5% carbon dioxide is called carbogen
(e) Carbon dioxide is used as a reducing agent in the extraction of pure metals from their corresponding ores.

Question 2.
Match the following.
Selina Concise Chemistry Class 8 ICSE Solutions - Carbon and Its Compounds 1
Answer:
Selina Concise Chemistry Class 8 ICSE Solutions - Water 12

Question 3.
How is carbon monoxide gas formed?
Answer:
Mostly carbon monoxide is formed when a large amount of carbon or its compounds is burnt in a limited supply of air or oxygen.
Selina Concise Chemistry Class 8 ICSE Solutions - Water 13

Question 4.
State the poisonous nature of carbon monoxide?
Answer:
Carbon monoxide is a highly poisonous gas. If air containing 0.5% carbon monoxide by volume is inhaled, death can result This is because carbon monoxide combines with the haemoglobin present in the blood cells of our body to form a stable compound called carboxyl-haemoglobin. This does not allow to absorb of oxygen. Thus depriving our body cells of oxygen. This cause obstruction in respiration and causes death.

Question 5.
Give two uses of carbon monoxide.
Answer:
Uses of carbon monoxide:

  • Carbon monoxide is a strong reducing agent.
  • Carbon monoxide is used in the extraction of pure metals from their ores.

Question 6.
Why is carbon monoxide called a silent killer?
Answer:
Carbon monoxide is produced by burning coal or wood in a limited supply of air. Since the gas is colourless and a barely detectable smell, people do not feel it and it can be proved as a silent killer.

Question 7.
Explain the reducing action of carbon monoxide.
Answer:
Reducing action of carbon- monoxide: Carbon monoxide is a strong reducing agent. It reduces the oxides of the less active metals to their respective metals and itself gets oxidised to carbon dioxide.
Selina Concise Chemistry Class 8 ICSE Solutions - Water 14

Question 8.
Write two remedies for carbon monoxide poisoning.
Answer:

  1. The victim should immediately be brought out into the open.
  2. The victim should be given artificial respiration with carbogen.

Question 9.
Complete the reactions and balance them.
(a) CuO + CO →
(b) Fe2O2 + CO →
Answer:

Selina Concise Chemistry Class 8 ICSE Solutions - Water 15

Selina Concise Physics Class 8 ICSE Solutions – Sound

Selina Concise Physics Class 8 ICSE Solutions – Sound

ICSE Solutions  Selina ICSE Solutions  ML Aggarwal Solutions

ICSESolutions.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Physics Chapter 7 Sound. You can download the Selina Concise Physics ICSE Solutions for Class 8 with Free PDF download option. Selina Publishers Concise Physics for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 8 Physics Chapter 7 Sound

  • SOUND: “Is energy which produces in us the sensation of hearing.” It is produced by vibration of body.
  • Sound needs a medium for its propagation. Sound cannot travel in vacuum.
  • Speed of sound is maximum in solids. 5000 ms-1 in steel, in water 1500 ms-1 and in air it is least 330 ms-1 nearly.
  • When a body vibrates, the particles of medium also start vibrating and K.E. of particles changes into potential energy and P.E. into
    K.E. This is why sound in energy.
  •  Sound travels in a medium in the form of wave.
    Selina Concise Physics Class 8 ICSE Solutions Chapter 7 Sound 1
  • Longitudinal wave : When the particles of medium move in the direction of motion of wave by forming compression and rarefaction.
    Selina Concise Physics Class 8 ICSE Solutions Chapter 7 Sound 2
  • AMPLITUDE : “The maximum displacement of the particle of medium on either side of mean position.”
    Selina Concise Physics Class 8 ICSE Solutions Chapter 7 Sound 3
  • TIME PERIOD: “The time taken by a particle of medium to complete its one vibration” “t”
  •  FREQUENCY: “The number of vibrations made by a particle of
    the medium in one second. ƒ measured in Hertz (Hz)
  •  FREQUENCY  ƒ = 1/ t or t = 1 / ƒ
  •  WAVE LENGTH: “The distance travelled by the wave in one one time period of vibration of particle of medium.”
    Or
    “The distance between two consecutive compressions or between two consecutive rarefactions.” It is denoted by ‘ λ ’ and S.I. unit of wave length is metre (m).
    Selina Concise Physics Class 8 ICSE Solutions Chapter 7 Sound 4
  •  CHARACTERISTICS OF SOUND :
    (i) Loudness.
    (ii) Pitch (or shrillness).
    (iii) Quality (or timbre or wave form).
    LOUDNESS : is the characteristic of sound by virtue of which a loud sound can be distinguished from a faint sound, both having same frequency and same wave form.
  •  It depend on: (i) Amplitude of wave (ii) Surface area of vibrating body (ii) Distance from the source of sound (iv) Sensitivity of listener: Unit of loudness is (dB) decibel.
  •  PITCH: It depends on number of vibrations per second or frequency : more frequency is high pitch shrilled sound and low frequency is flat sound.
  •  QUALITY: is the characteristic which distinguishes two sounds’of the same pitch and same loudness. It depends on wave form.

Test yourself

A. Objective Questions

1. Write true or false for each statement

(a) When sound propagates in air, it does not carry energy with it.
Answer. False.

(b) In a longitudinal wave, compression and rarefaction are formed.
Answer. True.

(c) The distance from one compression to nearest rarefaction is called wavelength.
Answer. False.

(d) The frequency is measured in second.
Answer. False.

(e) The quality of a sound depends on the amplitude of wave.
Answer. False.

(f) The pitch of sound depends on frequency.
Answer. True.

(g) Decibel is the unit of pitch of a sound.
Answer. False.

2. Fill in the blanks

(a) The time period of a wave is 2 s. Its frequency is 0.5 S-1.
(b) The pitch of a stringed instrument is increased by increasing tension in string.
(c) The pitch of a flute is decreased by increasing length of air column.
(d) Smaller the membrane, higher is the pitch.
(e) If a drum is beaten hard, its loudness increases.
(f) A tuning fork produces sound of single frequency.

3. Match the following
Selina Concise Physics Class 8 ICSE Solutions Chapter 7 Sound 5

4. Select the correct alternative

(a) Sound can not travel in

  1.  solid
  2.  liquid
  3.  gas
  4.  vacuum

(b) When sound travels in form of a wave

  1. the particles of medium move from the source to the listener
  2.  the particles of medium remains stationary
  3.  the particles of medium start vibrating up and down
  4.  the particles of medium transfer energy without leaving their mean positions.

(c) The safe limit of loudness of audible sound is

  1.  0 to 80 dB
  2.  above 80 dB
  3.  120 dB
  4.  above 120 dB

(d) The unit of loudness is

  1.  cm
  2.  second
  3.  hertz
  4.  decibel

(e) In a piano, pitch is decreased by

  1.  using thicker string
  2.  increasing tension
  3.  reducing length of string
  4.  striking it hard Ans.