ICSE Chemistry Question Paper 2008 Solved for Class 10

ICSE Chemistry Previous Year Question Paper 2008 Solved for Class 10

ICSE Paper 2008
CHEMISTRY

(Two Hours)
Answers to this Paper must be written on the paper provided separately.
You will not be allowed to write during the first 15 minutes.
This time is to be spent in reading the Question Paper.
The time given at the head of this Paper is the time allowed for writing the answers.
Section I is compulsory. Attempt any four questions from Section II.
The intended marks for questions or parts of questions are given in brackets [ ].

SECTION-I  (40 Marks)
(Attempt all questions from this Section)

Question 1:
(a) For part (a) (1) – (a) (10), select the correct answer from the choices A, B, C, D which are given. Write down only the letter corresponding to the correct answer.         [10]

1. With reference to the variation of properties in the Periodic Table, which of the following is generally true?
   (A) Atomic size increases from left to right across a period.
   (B) Ionization potential increases from left to right across a period.
   (C) Electron affinity increases going down a group.
   (D) Electro-negativity increases going down a group.
2. Which of the following is not a common characteristic of an electrovalent compound?
   (A) High melting point.
   (B) Conducts electricity when molten.
   (C) Consists of oppositely charged ions.
   (D) Ionizes when dissolved in water.
3. Dilute sulphuric acid will produce a white precipitate when added to a solution of:
   (A) Copper nitrate           (B) Zinc nitrate
   (C) Lead nitrate               (D) Sodium nitrate
4. The salt which in solution gives a pale green precipitate with sodium hydroxide solution and a white precipitate with barium chloride solution is:
   (A) Iron (III) sulphate         (B) Iron (II) sulphate
   (C) Iron (II) chloride           (D) Iron (III) chloride
5. The gas law which relates the volume of a gas to the number of molecules of the gas is:
   (A) Avogadro’s Law          (B) Gay-Lussac’s Law
   (C) Boyle’s Law                 (D) Charles’Law
6. During the electrolysis of molten lead bromide, which of the following takes place?
   (A) Bromine is released at the cathode
   (B) Lead is deposited at the anode
   (C) Bromine ions gain electrons
   (D) Lead is deposited at the cathode
7. Brass is an alloy of:
   (A) Copper and tin        (B) Copper and zinc
   (C) Zinc and lead           (D) Lead and tin
8. Ammonia can be obtained, by adding water to:
   (A) Ammonium chloride      (B) Ammonium nitrate
   (C) Magnesium nitrade         (D) Magnesium nitrate
9. Which, of the following reactions is used to prepare sulphuryl chloride? **
   (A) Adding concentrated sulphuric acid to a chloride.
   (B) Passing sulphur dioxide through a solution of chlorine.
   (C) Reacting dry sulphur dioxide and dry chlorine.
   (D) Beading dilute sulphuric acid with a solution of chlorine.
10. The formation of 1, 2-dibromethane from ethene and bromine is an example of:
    (A) Substitution                      (B) Dehydration
    (C) Dehydrohalogenation     (D) Addition

** Answer has not given due to out of present syllabus.

(b) The equation for the burning of octane is:
2C₈H₁₈ + 25O₂    →    16CO₂ + 18H₂O
(i) How many moles of carbon dioxide are produced when one mole of octane barns?
(ii) What volume, at sip, is occupied by the number of moles determined in (b) (i) ?
(iii) If the relative molecular mass of carbon dioxide is 44, what is the mass of carbon dioxide produced by burning two moles of octane?
(iv) What is the empirical formula of octane? [5]

(c) Name the organic compound prepared by each of the following reactions:

1. C₂H₅COONa + NaOH    →
2. CH₃I + 2H    →
3. C₂H₅Br + KOH (alcoholic solution)    →
4. CO + 2H₂ (Zinc oxide catalyst)    →
5. CaC₂ + 2H₂O   →                           [5]

(d) Identify the following substances:

1. An alkaline gas A which gives dense white fumes with hydrogen chloride.
2. A dilute acid B which does not normally give hydrogen when reacted with metals but, does give a gas when it reacts with copper.
3. Gas C has an offensive smell like rotten eggs
4. Gas D is a colourless gas which can be used as a bleaching agent. **
5. Liquid E can be dehydrated to produce ethane.     [5]
   ** Answer has not given due to out of present syllabus.

(e) Write the equation for the following reactions:
(i) Aluminium nitride and water.
(ii) Calcium carbide and water.
(iii) Ethene and water (steam).
(iv) Sulphur dioxide and water. **
(v) Bromoethane and an aqueous solution of sodium hydroxide. [5]

(f) Here is an electrode reaction:

1. Cu    →    Cu²⁺ + 2e^–
   At which electrode (anode or cathode) would such a reaction take place? Is this an example of oxidation or reduction?
2. A solution contains magnesium ions (Mg²⁺) iron (II) ions (Fe²⁺) and copper ions (Cu²⁺). On passing an electric current through this solution which ions will be the first to be discharged at the cathode? Write the equation for the cathode reaction.
3. Why is carbon tetrachloride, which is a liquid, a non-electrolyte? [5]

(g) What are the terms defined in (g) (1) – (5) below?

1. A bond formed by a shared pair of electrons, each bonding atom contributing one electron to the pair.
2. A bond formed by a shared pair of electrons with both electrons coming from the same atom.
3. A salt containing a metal ion surrounded by other ions or molecules.
4. A base which is soluble in water.
5. A reaction in which the hydrogen of an alkane is replaced by another element like chlorine.

Answer:
(a)

1. —B
2. —D
3. —C
4. —B
5. —A
6. —D
7. —B
8. —C
9. —D

(b) 

(c)

1. Ethane
2. Methane
3. ethene
4. methanol
5. Ethyne

(d)

1. Ammonia
2. Nitric acid
3. Hydrogen sulphide
5. Ethanol/Ethyl alcohol.

(f)

1. This reaction will take place at anode. It is an example of oxidation.
2. Cu⁺⁺ ions.
   Cu⁺⁺ + 2e^–    →    Cu (at cathode).
3. Carbon tetrachloride is a convalent compound.

(g)

1. Covalent bond
2. Co-ordinate bond.
3. Complex salt.
4. Alkali
5. Substitution.

SECTION-II  (40 Marks)
(Answer any four questions from this section)

Question 2:
Copy and complete the following table relating to important industrial processes. Output refers to the product of the process not the intermediate steps.

Answer:

Question 3:
The following questions refer to the Periodic Table:
(a)

1. Name the first and last element in period 2.
2. What happens to the atomic size of elements moving from top to bottom of a group?
3. Which of the elements has the greatest electron affinity among the halogens?
4. What is the common feature of the electronic configurations of the elements in group 7? [5]

(b) Supply the missing word from those in the brackets (Do not write out the sentence).

1. If an element has a low ionization energy then it is likely to be ……………. (metallic/non-metallic).
2. If an element has seven electrons in its outermost shell then it is likely to have the ……………. (largest/smallest) atomic size among all the elements in the same period. [2]

(c)

1. The metals of Group 2 from top to bottom are: Be, Mg, Ca, Sr, Ba. Which of these metals will form, ions most readily and why?
2. What property of an element is measured by electronegativity? [3]

Answer:
(a)

1. First element — Lithium
   Last element — Neon
2. It increases.
3. Chlorine.
4. Elements of seventh group have seven electrons in their valence shell.

(b)

1. metallic
2. smallest.

(c)

1. Ba will form ions most readily because it has lowest ionisation potential in group 2.
2. Electronegativity of an element is its relative tendency to attract the shared pair of electrons towards itself in a covalent bond.

Question 4:
(a) Distinguish between the saturated hydrocarbon ethane and the unsaturated hydrocarbon ethene by drawing their structural formulae. [2]
(b) Addition reactions and substitution reactions are types of organic reactions. Which type of reaction is shown by:
(1) ethane (2) ethene [2]
(c)

1. Write the equation for the complete combustion of ethane.
2. Using appropriate catalysts, ethane can be oxidized to an alcohol, an aldehyde and an acid. Name the alcohol, aldehyde and acid formed when ethane is oxidized. [4]

(d)

1. Why is pure acetic acid known as glacial acetic acid?
2. What type of compound is formed by the reaction between acetic acid and an alcohol?

Answer:
(a) Saturated hydrocarbon: Ethane has single covalent bond between carbon atoms.
Unsaturated hydrocarbon: Ethene has a double covalent bond between carbon atoms.

(b)

1. ethane     →    substitution reactions
2. ethene     →    addition reactions.

(c)

1. 2C₂H₆ + 7O₂   →    4CO₂ + 6H₂O
2. When ethene is oxidised, ethanol (C₂H₅OH), ethanal (CH₃CHO) and ethanoic acid (CH₃COOH) are formed.

(d)

1. Because on cooling pure acetic acid forms ice like crystals.
2. An ester is formed.

Question 5:
(a) (i) A compound has the, following percentage composition by mass:
carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. Determine the empirical formula of this compound. Work correct to 1 decimal place. (H = 1; C = 12; Cl = 35.5).
(ii) The relative molecular mass of this compound 168, so what is its molecular formula?
(iii) By what type reaction could this compound be obtained from ethyne? [6]

(b) From the equation
C + 2H₂SO₄    →    CO₂ + 2H₂O + 2SO₂
Calculate:
(i) The mass of carbon oxidized by 49 g of sulphuric acid (C = 12; relative molecular mass of sulphuric acid = 98).
(ii) The volume of sulphur dioxide measured at stp. liberated at the same time.
(Volume occupied by 1 mole of a gas at stp is 22.4 dm³)

Answer:
(a) (i)

Element	Percentage	At. Mass	Relative No.of atoms	Simplest ratio
C	14.4	12	14.4/12 = 1.2	1.2/1.2 = 1
H	1.2	1	1.2/1 = 1.2	1.2/1.2 = 1
Cl	84.5	35.5	84.5/35.5 = 2.4	2.4/1.2 = 2

Empirical formula = CHCl₂
(ii) Relative molecular mass = 168
Empirical formula mass = 12 + 1 + 71 = 84
\(n=\frac{\text{Relative molecular mass}}{\text{empirical formula mass }}=\frac{168}{84}=2\)
Molecular formula = (Empirical formula)_n
= (CHCl₂)₂
= C₂H₂Cl₄.
(iii) By addition reaction.

(b)

Question 6:
(a) The following is a sketch of an electrolytic cell used in the extraction of aluminium:

1. What is the substance of which the electrodes A and B are made?
2. At which electrode (A or B) is the aluminium formed?
3. What are the two aluminium compounds in the electrolyte C?
4. Why is it necessary for electrode B to be continuously replaced?

(b) Making use only of substances chosen from those given below:
Dilute sulphuric acid           sodium carbonate
Zinc                                         sodium sulphite
Lead                                        calcium carbonate
give the equations for the reactions by which you could obtain:
(i) hydrogen
(ii) sulphur dioxide **
(iii) carbon dioxide
(iv) zinc carbonate (two steps required)

Answer:
(a)

1. Graphite or carbon
2. At electrode A.
3. Alumina (Aluminium oxide) and Cryolite (sodium aluminium fluoride).
4. Because electrode B gets burnt away with oxygen produced.

Question 7:
(a)

1. What is the property of concentrated sulphuric acid which allows it to be used in the preparation of hydrogen chloride and nitric acid?
2. What property of hydrogen chloride is demonstrated when it is collected by downward delivery (upward displacement)?
3. Why is hydrogen chloride not collected over water?
4. What is the property of nitric acid which allows it to react with copper?
5. What property of concentrated sulphuric acid is in action when sugar turns black in its presence? [5]

(b) Write the equations for the following reactions:
(i) Dilute nitric acid and copper.
(ii) Dilute sulphuric acid and barium chloride.
(iii) Dilute hydrochloric acid and sodium thiosulphate.
(iv) Dilute hydrochloric acid and lead nitrate solution.
(v) Dilute sulphuric acid and sodium sulphide. [5]

Answer:
(a)

1. It is non-volatile.
2. Hydrogen chloride is heavier than air.
3. Because Hydrogen chloride is highly soluble in water.
4. It is a strong oxidising agent.
5. Cone. sulphuric acid is a dehydrating agent.

(b)

ICSE Class 10 Chemistry Previous Years Question Papers