ICSE Class 6 Chemistry Important Questions Chapter 2 States of Matter

Chemistry ICSE Class 6 Important Questions Chapter 2 States of Matter

Practice Questions

A. Define –
1. Volume
2. Mass
Answer:
1. The amount of space occupied by matter is called its volume.
2. The amount (quantity) of matter contained in an object or thing is known as its mass.

Question 2.
Name two factors which govern/decide the state of a matter.
Answer:

• Intermolecular force of attraction.
• Intermolecular space between the molecules of the matter.

Question 3.
Draw a diagram to show arrangement of molecules in solid, liquid and gas.
Answer:
The intermolecular force is the strongest in solids and weakest in gases. The intermolecular space is least, in solids (very closely packed) and largest in gases.

Question 4.
Why does a drop of ink spread slowly through the water when dropped in it ?
Answer:
It is because liquids can diffuse.
The intermolecular force of attraction is weak and the molecules in liquid can diffuse and mix with another liquid.

Question 5.
Give two examples of compressed gases.
Answer:
LPG (liquefied petroleum gas) and CNG (compressed natural gas)

Question 6.
Light an incense stick in a room. Its fragrance spreads throughout the room. Name the property of matter.
Answer:
Diffusion

Question 7.
Compare properties of solids, liquids and gases.
Answer:

Question 8.
Most substances can change from one state to another under different conditions of temperature and pressure. Explain with examples.
Answer:
Effect of change of temperature –
In normal conditions of temperature, water occurs in liquid state. On increasing the temperature, it changes into water vapour (gaseous state). When cooled, it changes back to water (liquid state). When temperature is decreased, it turns into ice (solid state). Hence, matter can be converted from one state to another under different conditions of temperature.

Effect of change of pressure :
On decreasing pressure, liquid changes into gas and on increasing pressure, a gas changes into its liquid state. When petroleum gas is filled into cylinders under high pressure, the gas changes into liquid state (LPG). When the LPG is released out of the cylinder, the pressure gets reduced and the liquid changes into its gaseous state.

Question 9.
Define –

1. Boiling point
2. Melting point
3. Condensation
4. Freezing.

Answer:

1. The temperature at which a liquid boils and changes rapidly into a gas is called the boiling point of the liquid.
2. The temperature at which a solid melts and changes to a liquid is called its melting point.
3. The process of conversion of the state of matter from vapour or gas into its liquid state on cooling is called condensation.
4. The process of conversion of the state of matter from liquid into its solid state by cooling is called freezing or solidification.

Question 10.
Give examples of solids that sublime.
Answer:
Iodine, solid carbon dioxide (dry ice), camphor, benzoic acid, naphthalene balls (moth balls).

Question 11.
What is difference between gas and vapour ?
Answer:
A substance which under a normal condition of temperature and pressure is a solid or liquid but changes to its gaseous state under specific conditions is called vapour. E.g., the gaseous state of water is water vapour and not water gas. A substance which exists in the gaseous state under normal condition of temperature and pressure is called a gas. Eg., oxygen, nitrogen, etc. are gases.

Question 12.
Fill in the blanks.
1. Matter is made up of very tiny particles called ……………
Answer:
Matter is made up of very tiny particles called atoms.

2. The intermixing of particles of different substances on their own is called ……………
Answer:
The intermixing of particles of different substances on their own is called diffusion.

3. Most substances can change from one state to another under different conditions of ……………. and
Answer:
Most substances can change from one state to another under different conditions of temperature and pressure.

4. ………….. in nature is an example of interconversion of states of matter.
Answer:
Water cycle in nature is an example of interconversion of states of matter.

5. Melting point of ice is ……………. and boiling point of pure water is ……………..
Answer:
Melting point of ice is 0°C and boiling point of pure water is 100°C.

6. Freezing point of a liquid is the same as the ……………… point of its solid state.
Answer:
Freezing point of a liquid is the same as the melting point of its solid state.

7. Boiling point of a liquid is the same as the ……………….. point of its vapour state.
Answer:
Boiling point of a liquid is the same as the condensation point of its vapour state.

8. The force of attraction between the molecules of a substance is called ……………..
Answer:
The force of attraction between the molecules of a substance is called intermolecular force of attraction.

9. The states of matter are …………………
Answer:
The states of matter are interconvertible.

B. Answer the following questions.

Question 1.
Gases can be compressed easily.
Answer:
The reason for this property of gases is that there is very large intermolecular space between gas molecules. On mere applying pressure, they are easily compressed.

Question 2.
Liquids can flow easily.
Answer:
In liquids intermolecular force is weaker than that of solids. So molecules in a liquids can slip over one another and liquids can flow unlike solids.

Question 3.
Silicon is considered a metalloid.
Answer:
Silicon is considered a metalloid because it has properties of both metals and non-metals.

Question 4.
We need to classify things.
Answer:
We need to classify things in order to distinguish them. In this way, things can be categorized and can be easily studied.

Question 5.
Pure substances have fixed melting or boiling points.
Answer:
Pure substances consists of only one kind of matter. All the particles of a pure substance are alike. It has a definite composition and similar properties. This is the reason that pure substances have fixed melting or boiling points.

Question 6.
Electricity is not considered matter.
Answer:
Electricity neither has mass nor it occupies space. Beside it can not be seen by our eyes. This is why electricity is not considered matter.

C. Define the following terms.

1. Matter
2. Intermolecular force
3. Element
4. Atom
5. Molecule
Answer:
1. Matter – Anything that has mass and occupies space is called matter.
2. Intermolecular force – The force of attraction between the molecules of a given substance is called intermolecular force.
3. Element – It is defined as that pure substance which contains only one type of atoms e.g. hydrogen, chlorine.
4. Atom – An atom is the smallest part of an element that takes place in a chemical reaction.
5. Molecule – A molecule is a smallest part of a compound that exists independently.

D. Differentiate between the following.

1. Liquids and gases
2. Atoms and molecules
3. Metals and non-metals
Answer:
1. Liquids and Gases
Liquids :

• Have definite volume but no definite shape
• Intermolecular force of attraction is weaker than that in solids
• Molecules are not as tightly packed as in solids and intermol-ecular space is more than that in solids.
• Molecules have no fixed position
• Can be compressed slightly
• Are capable of flowing

Gases :

• Have no definite shape or volume
• Intermolecular force of attraction is the weakest (almost negligible)
• Intermolecular space is the maximum and the molecules are far apart.
• Molecules move around freely
• Can be easily Compressed
• Can flow in all directions.

Question 2.
Atoms and Molecules
Answer:
Atoms :

• It is the smallest part of an element.
• It does not have independent existence

Molecules :

•  It is the smallest part of a compound.
• It has an independent existence.

Question 3.
Metals and Non-metals
Metals :

• They have lustre.
• They have high melting and boiling points.
• They are ductile.
• They are good conductors of heat and electricity.

Non-Metals :

• They lack lustre.
• They have low melting and boiling points.
• They are non-ductile.
• They are not good conductors of heat and electricity.

E. Write short answers.

Question 1.
Name the various states of matter.
Answer:
Solid, Liquid and gas

Question 2.
Name the two factors that influence the molecular arrangement of matter.
Answer:
1. Intermolecular space
2. Intermolecular attraction.

Question 3.
What is a compound ?
Answer:
A compound is a pure substance made up of two or more different elements.

Question 4.
What does a symbol represent ?
Answer:
Element

Question 5.
Classify the following elements as metals, non-metals and metalloids. Also, write their symbols.

1. Carbon
2. Arsenic
3. Copper
4. Gold
5. Silicon
6. Hydrogen

Answer:

1. Carbon = (C), Non metal
2. Arsenic = (As), Metalloid
3. Copper = (Cu), Metal
4. Gold = (Au), Metal
5. Silicon = (Si), Metalloid
6. Hydrogen = (H), Non metal

Question 6.
Give an example of a molecule of an element.
Answer:
(H₂) Hydrogen

Question 7.
Give the formula and constituents of the compound iron oxide.
Answer:
Formula of the compound = Fe₂O₂ Constituents = Iron and Oxygen

F. Answer in detail.

Question 1.
State the general properties of a solid.
Answer:
General Properties Of A Solid :

• Solids are hard that is, they have a definite shape and volume.
• Solids are generally incompressible.
• Solids are rigid, that is, they do not flow.

Question 2.
What is the relation between intermolecular space and intermolecular force ?
Answer:
The force of attraction between the molecules of a given substance is called intermolecular force and the space between these molecules is called intermolecular space. The basic relation between the two is that they are inversely : proportional to each other. More is the intermolecular force lesser is the intermolecular space and vice-versa.

Question 3.
Why liquids do not have a definite shape ?
Answer:
Molecules of a liquid are held by weak intermolecular forces. This force is strong enough to hold the molecules together but not strong enough to hold them at fixed positions. As a result liquids have a fixed volume but not shape.

Question 4.
What happens when a solid is heated ?
Answer:
When a solid is heated, its molecules gain energy and vibrate faster. A stage comes when they overcome intermolecular force of attraction and start moving from each other. This results in melting of solid.

Question 5.
State how matter can be classified.
Answer:
Matter is broadly classified into two groups – living and non living.

Now living matter can further be grouped as pure substances and mixtures. All pure substances have characteristic melting and boiling points. A pure substance can either be element or compound.

Question 6.
With a suitable example show that properties of a compound are totally different from those of the elements it is made up of.
Answer:
The best example for the above concept is water – H₂O. It is formed from hydrogen and oxygen gases.
Hydrogen is combustible and oxygen supports combustion whereas water stops combustion. H₂ and O₂ are gases and H₂O is liquid.

Question 7.
Metalloids are a mixture of metals and non-metals. Is it true ? Give reasons.
Answer:
Metalloids are elements that have properties of metals as well as non-metals, e.g., Silicon, germanium, arsenic, antimony etc. They are neither good nor bad conductors of electricity. Infact they are semi-conductors. They are neither very lustrous nor dull. Thus they are midway between Metals and Non Metals.

Question 8.
What are the characteristics of a compound ?
Answer:
Characteristics of A Compound :

• The properties of a compound are totally different from those of the elements it is made up of.
• Compounds are formed only when elements combine chemically in a fixed ratio.

Question 9.
Illustrate the IUPAC, rules for writing a chemical symbol?
Answer:
IUPAC RULES for chemical symbol :
Symbols of most of the elements correspond to the first letter of their English name.
When more than one element has the same initial letter in their names, then the symbol have two letters e.g. calcium – Ca Symbols of some elements are derived from their original Latin names e.g. Iron – Fe (Ferrum)

ICSE Class 6 Chemistry Important Questions