2011 WAEC (WASSCE) Chemistry Past Questions & Answers

Question 1

The energy change that accompanies the addition of an electron to an isolated gaseous atom is

Accepted Answer

C. electron affinity

Answer

A. bond energy

Answer

B. electronegativity

Answer

D. ionization energy

Question 2

What is the value of n in the following equation? Cr2O72- + 14H+ + ne- → 2Cr 3+ + 7H2O

Accepted Answer

C. 6

Answer

A. 2

Answer

B. 3

Answer

D. 7

Question 3

The reagent that can be used to distinguish ethene from ethyne is

Accepted Answer

A. ammoniacal silver trioxonitrate (V) solution

Answer

B. Benedict solution

Answer

C. bromine water

Answer

D. Fehling's solution

Question 4

When bromine is added to ethene at room temperature, the compound formed is

Accepted Answer

D. 1,2 - dibromoethane

Answer

A. 1,1 - dibromoethane

Answer

B. 1,2 - dibromoethene

Answer

C. 1,1 - dibromoethene

Question 5

The initial volume of a gas at 300 K was 220 cm 3 Determine its temperature if the volume became 250 cm 3

Accepted Answer

D. 341 K

Answer

A. 183 K

Answer

B. 264 K

Answer

C. 300 K

Question 6

Consider the reaction represented by the following equation: xKMnO 4(aq) + ySO2(g) + zH2O(I) → K 2SO4(AQ) + 2MnSO4(aq) + 2H2SO x,y and z are respectively

Accepted Answer

A. 2,5 and 2

Answer

B. 2,2 and 5

Answer

C. 5, 1 and 2

Answer

D. 1, 5 and 2

Question 7

When NH 4CI was dissolved in water, the container was cold to touch. This implies that

Accepted Answer

A. the process is endothermic

Answer

B. the process is exothermic

Answer

C. NH4CI is highly soluble in water

Answer

D. NH 4CI forms a saturated solution

Question 8

Chlorine, bromine and iodine belong to the same group and

Accepted Answer

D. react with alkali

Answer

A. are gaseous at room temperature.

Answer

B. form white precipitate with AgNO3(aq)

Answer

C. react violently with hydrogen without heating

Question 9

Rare gases are stable because they

Accepted Answer

D. have octet structure

Answer

A. contain equal number of protons and neutrons

Answer

B. contain more electrons than protons

Answer

C. are chemically active

Question 10

Which of the following compounds determines the octane rating of petrol?

Accepted Answer

D. 2,2,4 - trimethylpentane

Answer

A. 1,2,3 - trimethlpentane

Answer

B. 2,3,5 - trimethyloctane

Answer

C. 2,3,5 - trimethylpentane

Question 11

Which of the following elements would produce coloured ions in aqueous solution?

Accepted Answer

B. lron

Answer

A. Calcium

Answer

C. Magnesium

Answer

D. Sodium

Question 12

Which of the following elements can conveniently be placed in two groups in the periodic table ?

Accepted Answer

C. Hydrogen

Answer

A. Carbon

Answer

B. Copper

Answer

D. Oxygen

Question 13

Which of the following equimolar solutions has the highest conductivity?

Accepted Answer

C. H 2SO 4(aq)

Answer

A. CH3COOH(aq)

Answer

B. H2CO3(aq)

Answer

D. NaOH (aq)

Question 14

The following substances are ores of metals except

Accepted Answer

D. graphite

Answer

A. bauxite

Answer

B. cuprite

Answer

C. cassiterite

Question 15

An element with the electron configuration of 1s 22s 22p 6 would have a combining power of

Accepted Answer

A. o

Answer

B. 2

Answer

C. 6

Answer

D. 8

Question 16

Which of the following compounds would react with ethanoic acid to give a sweet smelling liquid?

Accepted Answer

B. Alkanol

Answer

A. Alkane

Answer

C. Alkanal

Answer

D. Alkyne

Question 17

Aluminium is extracted electrolysis from

Accepted Answer

A. bauxite

Answer

B. cryolite

Answer

C. duralumin

Answer

D. kaolin

Question 18

Which of the following hydrohalic acids is the weakest?

Accepted Answer

C. HF

Answer

A. HBr

Answer

B. HCI

Answer

D. HI

Question 19

The number of atoms in one mole of a substance is equal to the

Accepted Answer

D. avogadro number

Answer

A. mass number

Answer

B. oxidation number

Answer

C. atomic number

Question 20

Which of the following metallic oxides is amphoteric?

Accepted Answer

A. AI2O3

Answer

B. Fe2O3

Answer

C. MgO

Answer

D. Na2O

Question 21

Which of the following processes does not involve the use of limestone?

Accepted Answer

B. Manufacture of tetraoxosulphate (VI) acid by Contact process

Answer

A. Extraction of iron in the blast furnance

Answer

C. Production of washing  soda by Solvay process

Answer

D. Production of cement

Question 22

Which of the following metals could be used as sacrifical anode for preventing the corrosion of iron?

Accepted Answer

C. Magnesium

Answer

A. Copper

Answer

B. Lead

Answer

D. Silver

Question 23

When element 20A combines with element 8Y,

Accepted Answer

B. an ionic compound  AY is formed

Answer

A. a covalent compound, AY is formed

Answer

C. an ionic compound, A2Y is formed

Answer

D. a covalent compound, AY2 is formed

Question 24

What type of reaction is represented by the following equation?$\frac{2}{1}$D$\frac{3}{1}$H → $\frac{4}{4}$He + $\frac{1}{0}$n + energy

Accepted Answer

B. Nuclar fusion

Answer

A. Nuclear fission

Answer

C. Radioactive decay

Answer

D. Spontaneous decay

Question 25

Bubbling excess carbon (IV) oxide into calcium hydroxide solution results in the formaton of

Accepted Answer

B. Ca(HCO3)2

Answer

A. CaO

Answer

C. H2CO3

Answer

D. CaCO3

Question 26

Which of the following arrangements is in order of increasing metallic property?

Accepted Answer

A. Li < Na< k

Answer

B. Na < Li < K

Answer

C. K

Answer

D. K < Li < Na

Question 27

The volume occupied by 17g of H2S at s.t.p. is [H = 1.00, S = 32.0, Molar volume = 22.4 dm3]

Accepted Answer

A. 11.2dm 3

Answer

B. 17.0 dm3

Answer

C. 34.0dm 3

Answer

D. 44.8dm 3

Question 28

What is the amount of magnesium that would contain 1.20 x 1024 particles? [Mg = 24, Avogadro's constant = 6.02 x 1023]

Accepted Answer

B. 2.0 moles

Answer

A. 0.5 moles

Answer

C. 12.0 moles

Answer

D. 24.0 moles

Question 29

The compound that makes palm wine taste sour after exposure to the air for few days is

Accepted Answer

B. ethanoic acid

Answer

A. ethanol

Answer

C. methanol

Answer

D. methanoic acid

Question 30

Which of the following statements about enthalpy of neutralization is correct? It

Accepted Answer

A. is constant for a strong acid and a strong base

Answer

B. cannot be determined using calorimeter

Answer

C. has a positive value

Answer

D. is higher for strong acid and a weak base

Question 31

Which of the following ions has the electron configuration 2,8,8?

Accepted Answer

D. CI-

Answer

A. Na+

Answer

B. Mg2+

Answer

C. F-

Question 32

Which of the following statements about a molar solution is correct? it

Accepted Answer

D. contains one mole of the solute in 1 dm3 of solution

Answer

A. is a supersaturated solution

Answer

B. cannot dissolve more of the solute at that temperature

Answer

C. contains any amount of solute in a given volume of solution

Question 33

Which of the following statements about displacement reaction is correct?

Accepted Answer

A. A more electropositive element displaces a less electroposive one

Answer

B. A less electropositive element displaces a more electropositive one

Answer

C. The position of elements in the reactivity series has no effect on the reaction

Answer

D. it only occurs when the reaction is at equilibrium

Question 34

The colour of phenolphthalein indicator in alkaline solution at the end-point of an acid-base titration is?

Accepted Answer

C. pink

Answer

A. colourless

Answer

B. orange

Answer

D. yellow

Question 35

The bond formed when two electrons that are shared between two atoms are donated by only one of the atoms is

Accepted Answer

B. dative

Answer

A. covalent

Answer

C. ionic

Answer

D. metalic

Question 36

A gas that is collected by upward delivery is likely to be

Accepted Answer

C. lighter than air

Answer

A. heavier than air

Answer

B. insoluble in water

Answer

D. soluble in water

Question 37

Consider the following electrochemical cell notation: M(s) / M2+ (aq)// H+ (aq)/ H2(g). The value of the electrode potential is positive when?

Accepted Answer

A. electrons flow from the metal electrode, M(s) to hydrogen electrode, H2(g)

Answer

B. electrons fow from hydrogen electrode, H2(g) to metal electrode, M(s)

Answer

C. the flow of current is high

Answer

D. there is equilibrium between the flow of electrons from the hydrogen electrode, H2(g) to metal electrode, M(s)

Question 38

The equation P = $\frac{K}{V}$ illustrates

Accepted Answer

A. Boyle's law

Answer

B. Charles' law

Answer

C. Dalton's law

Answer

D. Gay Lussac's law

Question 39

How many isotopes has hydrogen?

Accepted Answer

B. 3

Answer

A. 2

Answer

C. 4

Answer

D. 5

Question 40

Which of the following electrons configurations correctly represents an inert element?

Accepted Answer

D. 1s22s22p6

Answer

A. 1s22s22p4

Answer

B. 1s22s22p63s2

Answer

C. 1s22s22p63s23p4

Question 41

What mass of copper would be formed when a current of 10.0 A is passed through a solution of CuSO4 for 1 hour? [Cu = 63.5; 1F = 96500C]

Accepted Answer

B. 11.8 g

Answer

A. 5.9 g

Answer

C. 23.8 g

Answer

D. 47.3 g

Question 42

The following substances are examples of addition polymer except

Accepted Answer

A. nylon

Answer

B. perspex

Answer

C. polyethene

Answer

D. polychloroethene

Question 43

Consider the following reaction equation: X(g) + Y(g) ⇌ XY(g); ∆H = + 220KJ $mol^{-1}$ If the temperature of the system is increased, the

Accepted Answer

B. forward reaction would favoured

Answer

A. backward reaction would be favoured

Answer

C. reaction would stop

Answer

D. reaction would be at equilibrium

Question 44

In metallic colids, the forces of attraction are between the mobile valence electrons and

Accepted Answer

D. positively charged nuclei

Answer

A. atoms

Answer

B. neutrons

Answer

C. the negative ions

Question 45

On evaporation to dryness, 250 cm3 of saturated solution of salt X with relative molar mass 101 gave 50.5g of the. What is the soluility of the salt?

Accepted Answer

B. 2.0 mol $dm^{-3}$

Answer

A. 1.0 mol $dm^{-3}$

Answer

C. 4.0 mol$dm^{-3}$

Answer

D. 5.0 mol$dm^{-3}$

Question 46

Which of the following separation techniques would show that black ink is a mixture of chemical compounds?

Accepted Answer

B. Chromatography

Answer

A. Crystallization

Answer

C. Filtration

Answer

D. Sublimation

2011 WAEC (WASSCE) Chemistry Past Questions

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