DISTINCT STAR INTERNATIONAL COLLEGE

MOCK EXAMINATION 2023/24 SESSION

Plot 11 – 12, Bankole Street, Magodo Phase 1 (Isheri), Lagos State
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SUBJECT: Chemistry TIME ALLOWED: 2 HR
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CLASS: YEAR 12 DATE: ___________________
STUDENT’S NAME [Surname first]:____________________________________________________________
GENERAL INSTRUCTIONS:
Read and follow the instructions carefully and strictly.
 Answer all the questions in Section 1 (Multiple choice questions)
 Answer all questions in Section 2 (Fill in the gap). You are to provide the correct
answer to each of the questions.
 For essay, study the instruction carefully and answer the questions as specified.
 Use soft pencils (HB or 2B) to draw.
 Write in Black/ Blue ink. Use a calculator, if permitted and specified.
 Write your surname, other names, class and date in the spaces provided at the top of
this paper.
 Write your name on every sheet of paper you are going to hand in.
 Write your name on the attendance sheet

For examiner’s use only

Questions Marks

Section A

Section B

Total
SECTION A (OBJECTIVE) A. CaO
1. How many isotopes has hydrogen? B. Ca(HCO3)2
A. 2 C. H2CO3
B. 3 D. CaCO3
C. 4
D. 5
7. The equation P = kV illustrates
2. Which of the following electrons A. Boyle's law
configurations correctly represents an inert B. Charles' law
element? C. Dalton's law
A. 1s22s22p4 D. Gay Lussac's law
B. 1s22s22p63s2
C. 1s22s22p63s23p4 8. The initial volume of a gas at 300 K was
D. 1s22s22p6 220 cm 3 Determine its temperature if the
volume became 250 cm3
3. Rare gases are stable because they A. 183 K
A. contain equal number of protons and B. 264 K
neutrons C. 300 K
B. contain more electrons than protons D. 341 K
C. are chemically active
D. have octet structure 9. Which of the following compounds
determines the octane rating of petrol?
4. Which of the following elements would A. 1,2,3 - trimethlpentane
produce coloured ions in aqueous B. 2,3,5 - trimethyloctane
solution? C. 2,3,5 - trimethylpentane
A. Calcium D. 2,2,4 - trimethylpentane
B. lron
C. Magnesium 10. Which of the following separation
D. Sodium techniques would show that black ink is a
mixture of chemical compounds?
5. A gas that is collected by upward A. Crystallization
delivery is likely to be B. Chromatography
A. heavier than air C. Filtration
B. insoluble in water D. Sublimation
C. lighter than air
D. soluble in water 11. The following substances are examples
6. Bubbling excess carbon (IV) oxide into of addition polymer except
calcium hydroxide solution results in the A. nylon
formaton of B. perspex
C. polyethene
D. polychloroethene 17. The crystal layers in graphite are held
together by
12. Aluminium is extracted electrolysis A. covalent bond
from B. electrostatic forces
A. bauxite C. ionic bond
B. cryolite D. van der Waal's forces
C. duralumin
D. kaolin 18. Which of the following arrangements is
in decreasing order of atomic radius?
13. Chlorine, bromine and iodine belong to A. Li>Be>C>
the same group and B. Li>B>Be>C
A. are gaseous at room temperature. C. Li>Be>B>C
B. form white precipitate with AgNO3(aq) D. C>B>Be>Li
C. react violently with hydrogen without
heating 19. The enzyme that catalyses the
D. react with alkali conversion of glucose te ethanol and
carbon (IV) oxide is
14. Which of the following elements can A. diastase
conveniently be placed in two groups in B. maltase
the periodic table? C. ptyalin
A. Carbon D. zymase
B. Copper
C. Hydrogen 20. A colourless hydrocarbon with a sweet
D. Oxygen smell undergoes substitution reaction. The
hydrocarbon is likely to be
15. The following substances are ores of A. alkanol
metals except B. benzene
A. bauxite C. ester
B. cuprite D. methane
C. cassiterite
D. graphite 21. Consider the reaction represented by
the following equation:
16. The shape of CH4 is C2H4(g) + 302(g) → 2CO2(g) + 2H2O(g)
A. linear How many moles of ethene would be
B. planar burnt to produce 0.1 mole of water?
C. pyramidal A. 0.05 mole
D. tetrahedral B. 0.10 mole
C. 0.20 mole C. 3517W
D. 2.00 moles D. 3518W

22. Which of the following salts on 27. If 0.20 mol dm-3 NaOH(aq) was
hydrolysis would give an alkaline solution? evaporated to yield 5.0g of solid NaOH,
A. NH4CI(s) calculate the volume of NaOH (aq) used. (Na
B. AICI3(s) = 23.0,O = 16:0; H = 1.00)
C. CH3COONa(s) A. 600cm-3
D. NH4NO3(s) B. 625cm3
C. 10003
23. Which of the following factors would D. 1600 cm 3
affect the equilibrium constant?
A. Concentration 28. Which of the following statements
B. Temperature about a chemical system in equilibrium is
C. Pressure correct/ The
D. Volume A. reaction is irreversible
B. reaction goes to completion
24. The type of energy changes that C. equilibrium is re-established when a
accompany the mixing of a strong acid to a stress is applied
strong base is D. equilibrium position is affected by
A. electrical catalyst
B. heat
C. light 29. The vapour pressure of a given volume
D. sound of liquid increase when the
A. liquid becomes saturated with a salt
25. Which of the following transition B. Volume of the liquid increases
metals is not attracted to external C. temperature of the liquid falls
magnetic field? D. temperature of the Liquid rises
A. Cu
B. Fe 30. Which of the following instruments is
C. Ti used in detecting the presence of
D. Zn radiation?
A. Cathode ray tube
26. An atom W has 17 electrons and 18 B. Geiger-Muller counter
neutrons. Which of the following C. Mass spectrometer
representations of the atom is correct? D. X-ray tube
A. 1718W
B. 1817W
31. The molecule which has a linear shape B. contain equal number of protons and
is neutrons
A. CH4 C. contain more electrons than protons
B. NH3 D. have octet structures
C. H2S
D. CO2 37. Bronze is a mixture of
A. Cu and Mg
32. The formula of the compound formed B. Cu and Sn
between a trivalent metal, M and a C. Cu and Zn
divalent non-metal, Y is D. Cu and Pb
A. M2Y3
B. M3Y2 38. The percentage by mass of calcium in
C. MY Ca(OCI)2 is [Ca = 40.0; CI = 35.5; O = 16.0]
D. M3Y A. 28.0%
B. 31.6%
33. An atom of an element X gains two C. 43.8%
electrons. The symbol of the ion formed is D. 44.5%
A. X +
B. X 2+ 39. Which of the following phenomenna
C. X 2- lead to decrease in volume of a liquid in an
D. X - open container?
A. Brownian motion
34. The element with electron B. Diffusion
configuration 1s2 2s2 2p6 3s2 3p1 belongs to C. Evaporation
A. s-block period 3, group 1 D. Sublimation
B. p-block, period 3, group 2
C. s-block, period 3, group 3 40. In the periodic table, alkaline earth
D. p-block, period 3, group 3 metals can be found in group
A. l
35. Which of the following halogens is B. ll
liquid at room temperature? C. VI
A. lodine D. VII
B. Chlorine
C. Bromine 41. Which of the following bond types is
D. Fluorine responsible for the high boiling point of
water?
36. Rare gases are stable because they A. Metallic bond
A. are chemically active B. Covalent bond
C. lonic bond [ C = 12.0, O = 16.0 ]
D. Hydrogen bond A. 0.20 mol
B. 0.25 mol
42. Kipps apparatus can be used to C. 0.40 mol
prepare? D. 0.50 mol
A. H2
B. NH3 47. The name of the compound
C. O2 CH3C(CH3)CH2CH2CH3
D. H2S A. 2 - methyl butane
B. 2,2 - dimethyl butane
43. Which of the following methods is NOT C. 2 - methyl pentane
used for the separation of mixtures? D. 2,2 - dimethyl pentane
A. Chromatography
B. Crystallization 48. The most suitable indicator for the
C. Distillation reaction between NaOH and HCOOH is?
D. Electrolysis A. bromocresol
B. methyl orange
44. If 6.5g of magnesium ribbon reacts C. methyl red
completely with Hydrochloric acid, how D. phenolphthalein
many grams of hydrogen gas would be
liberated? 49. If the value of ΔH is positive for a
Mg(s) + 2 HCl(aq) -->MgCl 2(aq) + H 2(g) reaction, it means that the reaction is?
[ H = 1.0, Mg = 24.0 ] A. exothermic
A. 0.54g B. endothermic
B. 0.70g C. spontaneous
C. 1.08g D. slow
D. 1.40g
50. An organic compound contains 72%
45. Calcium and magnesium belong to the carbon, 12% hydrogen and 16% oxygen by
group of the periodic table because both? mass. What is the empirical formula of the
A. are metals compound?
B. form cations [ H = 1.0. C = 12.0, O = 16.0 ]
C. form colourless salts A. C3H8O
D. have same number of valence electrons B. C6H12O
C. C6H12O2
46. How many moles of carbon (iv) D. C12H12O11
oxide contains 16.0g of oxygen?
SECTION B – THEORY
Answer question 1 and any other three questions (answer four questions in all)

1. (a)(i) Define ionic bond.

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(ii) What type of bond (s) exist (s) in:

I. magnesium oxide; ________________________________________________________
II. ammonium ion; __________________________________________________________

(b) Determine the oxidation number of sulphur in Na 2S2O2.

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(c) State Faraday's first law.

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(d) Give one example each of: (i) acid salt; (ii) base salt.
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(e) Name the type of energy change that occurs in each of the following processes
(i) I2(s) → I2(g): ____________________________________________________________
(ii) Cl(g) + e− → Cl−(g): _______________________________________________________

(f) State the effect of each of the following aqueous solutions on litmus paper:
(i) Na2SO4(aq): ____________________________________________________________
(ii) AlCl3(aq): ______________________________________________________________

(g) Define the term efflorescence.

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(h) Give two uses of activated charcoal.

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(i) State one use of each of the following processes in the chemical industry:
(i) hydrogenation of vegetable oil; ___________________________________________
(ii) cracking; _____________________________________________________________
(iii) esterification; _________________________________________________________

(j) Calculate the amount of silver deposited in moles when 10920 coulombs of electricity is
passed through a solution of a silver salt. [ Faraday constant-- 96500 C mol −1]
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2. (a) A hydrocarbon having the formula C10H22 was cracked to produce C6H14 and another
hydrocarbon P.
(i) Give the molecular formula of P: ________________________________________________
(ii) Draw the structures of two isomers of P.

(ii) Give a reason why P could be polymerized.

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(b) State the guiding principles/rule which are used to explain the way electrons of the atoms
of the elements are arranged in atomic orbitals.
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(c)Consider each of the following substances: NaH, H 2, H2S, NH4Cl.

(i) Describe the nature of the intermolecular forces holding the units or molecules together in
the condensed (liquid or solid) state.
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(ii) Explain briefly what happens when a sample of each of the substances is added to water.
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(iii) Write the chemical equations of any reactions occurring or of any equilibrium
established.
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(d) Element J has the following electron configuration: Is22s22p63s2.

(i) How many unpaired electrons can be found in J? __________________________________
(ii) State whether J would be a good oxidizing or reducing agent. ________________________
(iii) Give a reason for the answer in (d)(ii): ___________________________________________

3(a) (i) Define the term standard electrode potential.

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(ii) State three factors that affect the discharge of ions during electrolysis.
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(iii) State two functions of a salt bridge in an electrochemical cell.

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(b) Describe briefly what happens when a solution of copper (II) tetraoxosulphate (VI) is
electrolyzed using copper electrodes.
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c) Calculate the mass of copper deposited at the cathode when a current of 0.2A is passed
through a solution of copper (II) tetraoxosulphate (VI) for 35 minutes using copper
electrodes. [H = 1.00, O = 16.0, S = 32.0, Cu = 64.0, IF = 96,500C]
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(d)(i) State three characteristics of a catalyst.

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(ii) Name one manufacturing process in which each of the following metals is used as catalyst:
I. iron; II. nickel; Ill. platinum.
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4(a) (i) Define the term hygroscopic.

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(ii) Give two difference: between a physical change and a chemical change.
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(iii) Using the kinetic theory of gases, explain briefly the Charles' law.
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(b)(i) Arrange the following compounds in order of increasing boiling points: CS 2; CO2; NaH.
Give reasons for your answer.
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(ii) Write a balanced chemical equation to illustrate the reaction of chlorine gas with cold
dilute sodium hydroxide.

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(c) In a certain reaction, 15.0 g of impure magnesium sample reacted with excess hydrochloric
acid liberating 8.6 dm22 of hydrogen gas at s.t.p.
 (i) Write a balanced equation for the reaction.
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(ii) Calculate the: I. mass of pure magnesium in the sample; I. percentage purity of the
magnesium sample; III. number of ions produced in the reaction. [Mg = 24.0; volume at s.t.p.
22.4 dm−3, Avagadro's constant = 6.02 x 1023mol−1]
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5(a) Define each of the following terms:

(i) ion; (ii) isotopes.
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(b)(i) Consider the element 24 27

12 Mg and 13 Al
I. Write the electron configuration of each element.
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II. Explain briefly why the first ionization energy of 24 27

12 Mg is greater than that of 13 Al .
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(ii) Write the formulae of three different oxides of period 3 elements that react with water.
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(c)(i) What are allotropes?

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 (ii) Name the two crystalline allotropes of carbon.
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(iii) Give one industrial use of each allotrope named in (c)(ii).

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(d) On warming crystals of sodium chloride with concentrated tetraoxosulphate (VI) acid, a gas
was evolved.
(i) List two physical properties of the gas produced.
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(ii) Write a balanced equation for the reaction.

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(e) A certain chip W used in a circuit of a microcomputer has a mass of 5.68mg. Calculate the
amount of W in the microcomputer. [ W = 28 gmol−1].
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6(a)(i) Outline the steps involved in the purification of water for town supply.
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(ii) Give two cations that can cause hardness in water.

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(iii) State two disadvantages of hardness of water.

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(iv) List two sources of water pollution.
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(b) Explain briefly why water is a good solvent for sodium chloride but not for oil.
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(c) (i) Give the two products formed when chlorine water is exposed to sunlight.
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(ii) I. Which of the compounds is suitable for the preparation of standard alkaline solution?
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II. Give a reason for your answer in (c)(ii)I

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