JAMB Chemistry: practice questions.

Question 1 · Non-metals and their compounds

Dry chlorine does not bleach dry litmus paper, but moist chlorine bleaches it. This is because

1. A.dry chlorine is a reducing agent and needs water to become an oxidizing agent
2. B.moisture makes the chlorine colder so that it dissolves the dye more easily
3. C.with water, chlorine forms chloric(I) acid, which gives oxygen that oxidizes the dye
4. D.water itself is the strong bleaching agent, and chlorine only acts as a catalyst

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Question 2 · Acids, bases and salts

The sour taste of lime and lemon juice used in making zobo drink is due mainly to

1. A.ethanoic acid
2. B.tartaric acid
3. C.lactic acid
4. D.citric acid

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Question 3 · Atomic structure and bonding

Millikan's oil-drop experiment was used to determine

1. A.the mass of a proton
2. B.the charge-to-mass ratio of the electron
3. C.the atomic number of an element
4. D.the charge on an electron

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Question 4 · Chemical equilibria

Changing the pressure would have NO effect on the equilibrium position of which reaction?

1. A.N₂(g) + 3H₂(g) ⇌ 2NH₃(g)
2. B.2SO₂(g) + O₂(g) ⇌ 2SO₃(g)
3. C.N₂O₄(g) ⇌ 2NO₂(g)
4. D.H₂(g) + I₂(g) ⇌ 2HI(g)

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Question 5 · Organic compounds

Which reagent distinguishes propanal from propanone?

1. A.Bromine water, which is decolorized by both compounds
2. B.2,4-dinitrophenylhydrazine: orange precipitate with propanone only
3. C.Tollens' reagent: a silver mirror with propanal only
4. D.Sodium hydrogentrioxocarbonate(IV): effervescence with propanal only

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Question 6 · Kinetic theory of matter and gas laws

The random zig-zag movement of pollen grains suspended in water, seen under a microscope, provides evidence that

1. A.water molecules are in constant random motion
2. B.pollen grains are alive and swimming about in the water
3. C.water is a compound of the elements hydrogen and oxygen
4. D.the pollen grains are slowly dissolving in the water

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Question 7 · Atomic structure and bonding

The line spectrum of hydrogen is best explained by Bohr's idea that

1. A.electrons are spread uniformly through a sphere of positive charge, like a plum pudding
2. B.the nucleus emits light of all colours when the atom is strongly heated
3. C.atoms are indivisible particles that cannot be broken into anything smaller
4. D.electrons occupy definite energy levels and emit energy only on moving between them

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Question 8 · Nuclear chemistry

The correct order of increasing penetrating power of radiations is

1. A.gamma < beta < alpha
2. B.alpha < beta < gamma
3. C.beta < alpha < gamma
4. D.alpha < gamma < beta

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Question 9 · Rates of chemical reaction

Excess marble chips react with 50 cm³ of 1.0 mol/dm³ hydrochloric acid, and the final volume of carbon(IV) oxide is V. The experiment is repeated with 50 cm³ of 2.0 mol/dm³ acid and the same excess of marble at the same temperature. Compared with the first experiment, the second

1. A.is faster, and gives the same final volume V
2. B.is slower, but still gives a final volume of 2V
3. C.is faster, and gives a final volume of 2V
4. D.has the same rate, and gives a final volume of V/2

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Question 10 · Chemical equilibria

For the equilibrium N₂O₄(g) ⇌ 2NO₂(g), the equilibrium constant K is

1. A.[N₂O₄] / [NO₂]²
2. B.[NO₂]² / [N₂O₄]
3. C.2[NO₂] / [N₂O₄]
4. D.[NO₂] / [N₂O₄]

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Question 11 · Environmental pollution

Several family members slept in a closed room in Kano with a petrol generator running nearby and were found unconscious. The gas most likely responsible is

1. A.carbon(IV) oxide, which is highly poisonous even in very small amounts
2. B.nitrogen, which displaces oxygen from the lungs of people asleep
3. C.sulphur(IV) oxide, which forms acid rain and burns the lining of the lungs
4. D.carbon(II) oxide, which binds to haemoglobin and stops it carrying oxygen

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Question 12 · Non-metals and their compounds

Ozone in the upper atmosphere is important because it

1. A.is the main source of oxygen for respiration
2. B.traps infra-red radiation to warm the earth
3. C.absorbs harmful ultraviolet radiation from the sun
4. D.removes carbon(IV) oxide from the air

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