2013 WAEC (WASSCE) Chemistry Past Questions & Answers

Question 1

Which of the following phenomenna lead to decrease in volume of a liquid in an open container?

Accepted Answer

C. Evaporation

Answer

A. Brownian motion

Answer

B. Diffusion

Answer

D. Sublimation

Question 2

Which of the following raw materials is used in a plastic industry?

Accepted Answer

A. Ethene

Answer

B. Methane

Answer

C. Calcium

Answer

D. Hydrogen

Question 3

Which of the following organic compounds would decolourize bromie water?

Accepted Answer

B. Cyclobutane

Answer

A. Benzene

Answer

C. Hexane

Answer

D. Pentane

Question 4

The aqueous solution which has pH > 7 is

Accepted Answer

D. Na2CO3(aq)

Answer

A. FeCI3(aq)

Answer

B. CuSO4(aq)

Answer

C. KNO3(aq)

Question 5

Which of the following compounds crystallizes without water of crystallization?

Accepted Answer

C. NaCI

Answer

A. MgSO4

Answer

B. Na2CO3

Answer

D. FeSO4

Question 6

A hydrocarbon compound contains 92.3% carbon Determine its empirical formula [H = 1.00; C = 12.0]

Accepted Answer

A. CH

Answer

B. CH2-

Answer

C. CH3

Answer

D. C3H2

Question 7

Consider the redox reaction as represented by the following equation: 12(aq) + 2S2O32-(aq) → 21-(aq) + S4O62-(aq). Which of the species in the equation is reduced?

Accepted Answer

C. 12(aq)

Answer

A. S4O62-(aq)

Answer

B. S4O32-(aq)

Answer

D. 1-(aq)

Question 8

Which of the following gases are arranged in increasing order of diffusion rate? [H = 1 .0; C = 12; N = 14; O = 16; S = 32]

Accepted Answer

A. SO 2 O2, NH3 H2

Answer

B. H2S,NH2,O2,SO2

Answer

C. CO2,N2O,O2,SO2

Answer

D. NH3,NO2,N2,CO2

Question 9

In metallic solid, the forces of attraction is between the mobile valence electrons and the

Accepted Answer

D. positively charged nuclei

Answer

A. atoms

Answer

B. neutrons

Answer

C. negative ions

Question 10

Noble gas molecules are held together by

Accepted Answer

A. van der Waals forces

Answer

B. hydrogen bonds

Answer

C. dative bonds

Answer

D. covalent bonds

Question 11

The pressure exerted by a gas is a function of the

Accepted Answer

D. frequency of collision between gaseous molecules

Answer

A. total volume of the gas

Answer

B. speed of the gaseous molecules

Answer

C. mass of each gaseous molecule

Question 12

When heat is absorbed during a chemical reaction, the reaction is said to be

Accepted Answer

B. endothermic

Answer

A. adiabatic

Answer

C. exothermic

Answer

D. isothermal

Question 13

Which of the following statements is correct?

Accepted Answer

D. Cations are smaller than the parent atom

Answer

A. Atomic size decreases down the group

Answer

B. Atomic size increases across the period

Answer

C. Anions are smaller than the parent atom

Question 14

Which of the following halogens is liquid at room temperature?

Accepted Answer

C. Bromine

Answer

A. lodine

Answer

B. Chlorine

Answer

D. Fluorine

Question 15

The separation of petroleum fractions depends on the differences in their

Accepted Answer

D. boiling points

Answer

A. melting points

Answer

B. molar masses

Answer

C. solubilities

Question 16

Which of the following statements about nuclear reaction is correct? The reaction

Accepted Answer

B. takes place inside the nucleus

Answer

A. involves neutrons only

Answer

C. is governed by temperature and pressure

Answer

D. involves protons  and electrons only

Question 17

The major product formed by the reaction between ethanoic acid and aqueous sodium hydroxide is

Accepted Answer

B. sodium ethanoate

Answer

A. soap

Answer

C. sodium methoxide

Answer

D. water

Question 18

The gas law which describes the relationship between volume and temperature is

Accepted Answer

B. Charles' law

Answer

A. Boyle's law

Answer

C. Dalton's law

Answer

D. Graham's law

Question 19

Which of the following materials is classified as a non-biodegradable pollutant?

Accepted Answer

C. Plastic

Answer

A. Animal hide

Answer

B. Paper

Answer

D. Wood

Question 20

Which of the following cells produce electrical energy from chemical reactions? l. Lead-acid battery ll. Dry cell III. Deniell cell IV Electrolytic cell

Accepted Answer

B. l, ll, and III only

Answer

A. l and ll only

Answer

C. lll and IV only

Answer

D. I and III only

Question 21

The percentage by mass of calcium in Ca(OCI)2 is [Ca = 40.0; CI = 35.5; O = 16.0]

Accepted Answer

A. 28.0%

Answer

B. 31.6%

Answer

C. 43.8%

Answer

D. 44.5%

Question 22

Which of the following acids would readily react with CaCO3 to liberate CO2?

Accepted Answer

D. HNO3

Answer

A. CH3COOH

Answer

B. H2SO4

Answer

C. H2SO3

Question 23

Which of the following bond types is responsible for the high boiling point of water?

Accepted Answer

D. Hydrogen bond

Answer

A. Metallic bond

Answer

B. Covalent bond

Answer

C. lonic bond

Question 24

In which of the following series are the atoms arranged in order of increasing ionization energy?

Accepted Answer

C. O, F, Ne

Answer

A. Li, Na K

Answer

B. B, Be, Li

Answer

D. Be, mG, Ca

Question 25

Bronze is a mixture of

Accepted Answer

B. Cu and Sn

Answer

A. Cu and Mg

Answer

C. Cu and Zn

Answer

D. Cu and Pb

Question 26

Which of the following reactions is common to all hydrocarbones?

Accepted Answer

A. Combustion

Answer

B. Addition

Answer

C. Polymerization

Answer

D. Condensation

Question 27

The bonds in crystalline ammonium chloride are

Accepted Answer

C. ionic, covalent and dative

Answer

A. covalent and dative

Answer

B. ionic and covalent

Answer

D. ionic, covalent and hydrogen bond

Question 28

Which of the following instruments is used in detecting the presence of radiation?

Accepted Answer

B. Geiger-Muller counter

Answer

A. Cathode ray tube

Answer

C. Mass spectrometer

Answer

D. X-ray tube

Question 29

An atom of an element X gains two electrons. The symbol of the ion formed is

Accepted Answer

C. X 2-

Answer

A. X +

Answer

B. X 2+

Answer

D. X -

Question 30

Which of the following arrangements represents the correct order of electronic energy level?

Accepted Answer

C. 1s 2s 2p 3s 3p 4s 3d

Answer

A. 1s 2p 2s 3p 3s 3d 4s

Answer

B. 1s 2s 2p 3s 3p 3d 4s

Answer

D. 1s 2s 3s 2p 3p 4s 3d

Question 31

Consider the reaction represented by the following equation: C$_2$H$_2$ + yH$_2$ → C$_2$H$_6$. The value of y in the reaction is

Accepted Answer

C. 2

Answer

A. 4

Answer

B. 3

Answer

D. 1

Question 32

How many isomers has C$_3$H$_6$CI$_2$?

Accepted Answer

C. 4

Answer

A. 2

Answer

B. 3

Answer

D. 5

Question 33

A substance is said to be impure if

Accepted Answer

A. its melting point range is wide

Answer

B. it dissolves in water with difficult

Answer

C. it has a low melting point

Answer

D. it is coloured

Question 34

In the periodic table, alkaline earth metals can be found in group

Accepted Answer

B. ll

Answer

A. l

Answer

C. VI

Answer

D. VII

Question 35

Consider the reaction represented by the equation: N$_2$O$_4$(g) ⇌ 2NO$_2$(g) ; ∆H = + x kJ$mol^{-1}$ What happens when the temperature is reduced at equilibrium?

Accepted Answer

B. Concentration of N 2O4(g) increases.

Answer

A. Concentration of N 2O4(g) decreases

Answer

C. Pressure exerted by the gases increases

Answer

D. Pressure exerted by the gases remains constant

Question 36

Which of the following variables is a measure of the average kinetic energy of the molecule of a gas?

Accepted Answer

C. Temperature

Answer

A. Density

Answer

B. Pressure

Answer

D. Volume

Question 37

The main function of limestone in the blast furnace is to

Accepted Answer

C. remove impurity

Answer

A. act as catalyst

Answer

B. act as reducing agent

Answer

D. supply carbon (IV) oxide

Question 38

The element with electron configuration 1s$^2$ 2s$^2$ 2p$^6$ 3s$^2$ 3p$^1$ belongs to

Accepted Answer

D. p-block, period 3, group 3

Answer

A. s-block period 3, group 1

Answer

B. p-block, period 3, group 2

Answer

C. s-block, period 3, group 3

Question 39

The formula of the compound formed between a trivalent metal, M and a divalent non-metal, Y is

Accepted Answer

A. M2Y3

Answer

B. M3Y2

Answer

C. MY

Answer

D. M3Y

Question 40

The volume of 0.25 mol$dm^{-3}$ solution of KOH that would yield 6.5g of of solid KOH on evaporation is (K = 39.0; o = 16.0; H = 1.00)

Accepted Answer

A. 464.30 cm3

Answer

B. 625.00 cm3

Answer

C. 1000.00 cm3

Answer

D. 2153.80 cm3

Question 41

The molecule which has a linear shape is

Accepted Answer

D. CO2

Answer

A. CH4

Answer

B. NH3

Answer

C. H2S

Question 42

Which of the following elements is diatomic?

Accepted Answer

B. Oxygen

Answer

A. Sodium

Answer

C. Iron

Answer

D. Neon

Question 43

Which of the following statements about fine chemical is correct? It

Accepted Answer

C. is produced in relatively small amount

Answer

A. is injurious to health

Answer

B. has low degree of purity

Answer

D. can be stored for a long time

Question 44

Which of the following statements about thermoplastic material is correct? They

Accepted Answer

D. soften and melt on heating

Answer

A. do not melt on heating

Answer

B. harden on heating

Answer

C. decompose on heating

Question 45

Rare gases are stable because they

Accepted Answer

D. have octet structures

Answer

A. are chemically active

Answer

B. contain equal number of protons and neutrons

Answer

C. contain more electrons than protons

Question 46

The following factors affect the solubility of a solid in a given solvent except

Accepted Answer

C. pressure

Answer

A. nature of solute

Answer

B. nature of solvent

Answer

D. temperature

Question 47

In the periodic table all elements within the same group have the same

Accepted Answer

B. number of valence electrons

Answer

A. number of neutrons

Answer

C. number of isotopes

Answer

D. atomic number

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