JAMB Chemistry 1991 past questions and answers

Which of the following can be obtained by fractional distillation?

1. A.Nitrogen from liquid air
2. B.Sodium chloride from sea water
3. C.Iodine from a solution of iodine in carbon tetrachloride
4. D.Sulphur from a solution of sulphur in carbon disulphide.

Which of the following are mixtures? i. Petroleum ii. Rubber latex. iii. Vulcanizer's solution iv. Carbon (II) sulphide

1. A.i, ii and iii
2. B.i, ii and iv
3. C.i and ii only
4. D.i and iv.

An iron ore is known to contain 70.0% Fe₂O₃. The mass of iron metal which can be theoretically be obtained from 80 kg of the ore is [Fe = 56, O = 16].

1. A.35.0 kg
2. B.39.2kg
3. C.70.0 kg
4. D.78.4 kg

In two separate experiments, 0.36 g and 0.71 g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20 g and 0.40 g of X respectively. The data above represents the law of

1. A.multiple proportion
2. B.conservation of mass
3. C.constant composition
4. D.reciprocal proportion

A given quantity of a gas occupies a volume of 228 cm³ at a pressure of 750 mm Hg. What will be its volume at atmospheric pressure?

1. A.220 cm³
2. B.225 cm³
3. C.230 cm³
4. D.235 cm³

Calculate the volume of carbon (IV) oxide measured at s.t.p, produced when 1 kg of potassium hydrogen trioxocarbonate (IV) is totally decomposed by heat. [G.M.V. at s.t.p = 22.4 dm³, K = 39, O = 16, C = 12, H = 1].

1. A.28 dm³
2. B.56 dm³
3. C.112 dm³
4. D.196 dm³

A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm³ container at 20°C. The number of moles of gas in the sample is [R = 0.082 litre atm / deg mole].

1. A.1.00
2. B.2.00
3. C.3.00
4. D.4.00

Atoms of element X (with 2 electrons in the outer shell) combine with atoms of Y (with 7 electrons in the outer shell). Which of the following statements is FALSE? The compound formed

1. A.has formula XY
2. B.is likely to be ionic
3. C.contains X²⁺ ions
4. D.contains Y⁻ ions.

The ions X⁻ and Y⁺ are isoelectronic, each containing a total of 10 electrons. How many protons are in the nuclei of the neutral atoms of X and Y respectively?

1. A.10 and 10
2. B.9 and 9
3. C.11 and 9
4. D.9 and 11

The electronic configuration of an element is 1s²2s²2p⁶3s²3p³. How many unpaired electrons are there in the element?

1. A.5
2. B.4
3. C.3
4. D.2.

Which of the following represents the type of bonding present in ammonium chloride molecule?

1. A.Ionic only
2. B.Covalent only
3. C.Ionic and dative covalent
4. D.Dative covalent only

Which of the following is arranged in order of increasing electronegativity?

1. A.Chlorine, aluminium, magnesium, phosphorus, sodium.
2. B.Sodium, magnesium, aluminium, phosphorus, chlorine
3. C.Chlorine, phosphorous, aluminium, magnesium, sodium.
4. D.Sodium, chlorine, phosphorus, magnesium, aluminium

A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of

1. A.nitrogen
2. B.neon
3. C.argon
4. D.oxygen

The electrons of two atoms Y and Z are arranged in shells as shown above. The bond formed between the atoms of Y and Z is

1. A.ionic
2. B.covalent
3. C.dative
4. D.metallic.

Which of the following ions is a pollutant in drinking water even in trace amounts?

1. A.Ca²⁺
2. B.Hg²⁺
3. C.Mg²⁺
4. D.Fe²⁺

The solubility of copper (II) tetraoxosulphate (VI) is 75 g in 100 g of water at 100°C and 25 g in 100 g of water at 30°C. What mass of the salt would crystallize, if 50 g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C?

1. A.57.5 g
2. B.42.9 g
3. C.28.6 g
4. D.14.3 g

A sample of temporary hard water can be prepared in the laboratory by

1. A.dissolving calcium chloride in distilled water
2. B.saturating lime water with carbon (IV) oxide
3. C.saturating distilled water with calcium hydroxide
4. D.dissolving sodium hydrogen trioxocarbonate (IV) in some distilled water.

A property of a colloidal dispersion which a solution does not have is

1. A.the Tyndall effect
2. B.homogeneity
3. C.osmotic pressure
4. D.surface polarity

50 cm³ of sulphur (IV) oxide, 800 cm³ of ammonia, 450 cm³ of hydrogen chloride, 1.0cm³ of carbon (IV) oxide will respectively saturate 1.0 cm³ of water at 15°C. Which of the following is suitable for demonstrating the fountain experiment?

1. A.Sulphur (IV) oxide and hydrogen chloride.
2. B.Carbon (IV) oxide and ammonia
3. C.Ammonia and hydrogen chloride
4. D.Carbon (IV) oxide and sulphur (IV) oxide.

A simple cell (figure above): a zinc plate and a copper plate dip into substance X, connected to a bulb. Which of the following substances could be satisfactorily used as X in the above figure?

1. A.Ammonia and potassium hydroxide
2. B.Potassium hydroxide and sodium chloride.
3. C.Ammonia and ethanoic acid
4. D.Ethanoic acid and sodium chloride.

What volume of CO₂ at s.t.p would be obtained by reacting 10 cm³ of 0.1 M solution of anhydrous sodium trioxocarbonate (IV) with excess acid? [G.M.V at s.t.p = 22.4 dm³]

1. A.2.240 cm³
2. B.22.40 cm³
3. C.224.0 cm³
4. D.2240 cm³.

If a current of 1.5 A is passed for 4.00 hours through a molten tin salt and 13.3 g of tin is deposited, what is the oxidation state of the metal in the salt? [Sn = 118.7, F = 96500 C mol⁻¹].

1. A.1
2. B.2
3. C.3
4. D.4

Which of the following equimolar solutions, Na₂CO₃, Na₂SO₄, FeCl₃, NH₄Cl and CH₃COONa, have pH greater than 7?

1. A.FeCl₃ and NH₄Cl
2. B.Na₂CO₃, CH₃COONa and Na₂SO₄
3. C.Na₂CO₃ and CH₃COONa
4. D.FeCl₃, CH₃COONa and NH₄Cl.

MnO₄⁻ + 8H⁺ + ne → Mn²⁺ + 4H₂O. Which is the value of n in the reaction above?

1. A.2
2. B.3
3. C.4
4. D.5

2H₂S_(g) + SO_2(g) → 3S_(s) + 2H₂O_(l). The above reaction is

1. A.a redox reaction in which H₂S is the oxidant and SO₂ is the reductant
2. B.a redox reaction in which SO₂ is the oxidant and H₂S is the reductant
3. C.not a redox reaction because there is no oxidant in the reaction equation
4. D.not a redox because there is no reductant in the reaction equation.

Manganese (IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to

1. A.increase the surface area of the reactants
2. B.increase the concentration of the reactants
3. C.lower the activation energy for the reaction
4. D.lower the heat of reaction, ΔH, for the reaction

1.1 g of CaCl₂ dissolved in 50 cm³ of water caused a rise in temperature of 3.4°C. The heat of reaction, ΔH for CaCl₂ in kJ per mole is [Ca = 40, Cl = 35.5, specific heat of water is 4.18 JK⁻¹].

1. A.−71.1
2. B.−4.18
3. C.+71.1
4. D.+111.0

NO_(g) + CO_(g) ⇌ ½N_2(g) + CO_2(g) ΔH = −89.3 kJ. What conditions would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?

1. A.Low temperature and high pressure
2. B.High temperature and low pressure
3. C.High temperature and high pressure
4. D.Low temperature and low pressure.

Which of the following equilibria is unaffected by a pressure change?

1. A.2NaCl_(s) ⇌ 2Na_(l) + Cl_2(g)
2. B.H_2(g) + I_2(g) ⇌ 2HI_(g)
3. C.2O_3(g) ⇌ 3O_2(g)
4. D.2NO_2(g) ⇌ N₂O_4(g).

Initial concentration of NO in moles: 0.001, initial rate (moles / sec): 3.0 × 10⁻⁵
Initial concentration of NO in moles: 0.002, initial rate (moles / sec): 1.2 × 10⁻⁴
The data in the table above shows the rate of reaction of nitrogen (II) oxide with chlorine at 25°C. It can be concluded that doubling the initial concentration of NO increases the rate of reaction by a factor of

1. A.two
2. B.three
3. C.four
4. D.five

Which of the following gases will rekindle a brightly glowing splint?

1. A.NO₂
2. B.NO
3. C.N₂O
4. D.Cl₂.

Which of the following salts can be melted without decomposition?

1. A.Na₂CO₃
2. B.CaCO₃
3. C.MgCO₃
4. D.ZnCO₃.

Oxygen gas can be prepared by heating

1. A.ammonium trioxonitrate (V)
2. B.ammonium trioxonitrate (III)
3. C.potassium trioxonitrate (V)
4. D.manganese (IV) oxide.

Addition of aqueous ammonia to a solution of Zn²⁺ gives a white precipitate which dissolves in an excess of ammonia because

1. A.zinc is amphoteric
2. B.zinc hydroxide is readily soluble
3. C.zinc forms a complex which is readily soluble in excess ammonia
4. D.ammonia solution is a strong base.

Which of the following, in clear solution, forms a white precipitate when carbon (IV) oxide is bubbled into it for a short time?

1. A.KOH
2. B.NaOH
3. C.Ca(OH)₂
4. D.Al(OH)₃.

Copper (II) tetraoxosulphate (VI) is widely used as a

1. A.fertilizer
2. B.fungicide
3. C.disinfectant
4. D.purifier

Which of the following metals can be prepared in samples by the thermal decomposition of their trioxonitrate (V) salts?

1. A.Copper and mercury
2. B.Silver and copper
3. C.Mercury and silver
4. D.Magnesium and mercury

Which of the following compounds can exist as geometric isomers?

1. A.2-methylbut-2-ene.
2. B.But-2-ene
3. C.But-1-ene
4. D.CI—C—Br with I above and I below the carbon

How many structural isomers can be written for the alkyl bromide, C₄H₉Br?

1. A.3
2. B.4
3. C.6
4. D.8

The final products of the reaction between methane and chlorine in the presence of ultraviolet light are hydrogen chloride and

1. A.chloromethane
2. B.tetrachloromethane
3. C.trichloromethane
4. D.dichloromethane

How many grams of bromine will be required to completely react with 10 g of propyne? [C = 12, H = 1, Br = 80].

1. A.20g
2. B.40 g
3. C.60 g
4. D.80 g

Ethene when passed into concentrated H₂SO₄ is rapidly absorbed. The product is diluted with water and then warmed to produce

1. A.ethanol
2. B.diethyl ether
3. C.ethanal
4. D.diethyl sulphate

One of the advantages of detergents over soap is that detergents

1. A.are easier to manufacture
2. B.foam more than soap
3. C.form soluble salts with hard water
4. D.are able to deter germs more than soap.

CH₃CH₂CHXCH₃ (alc. KOH) → CH₃CH = CHCH₃ + CH₃CH₂CH = CH₂
The above reaction is an example of

1. A.dehydration
2. B.dehydrohalogenation
3. C.neutralization
4. D.a fission reaction

A certain liquid has a high boiling point. It is viscous, non-toxic, miscible with water being very hygroscopic. This liquid is most likely to be

1. A.CH₃CH₂CH₂OH
2. B.CH₃CHOHCH₃
3. C.CH₃CH₂CHOHCH₃
4. D.CH₂OHCHOHCH₂OH

The compound CH₃—CH(CH₂Cl)—CH₃ is known as

1. A.1-chloro-2-methylbutane
2. B.1-chloro-2-methylpropane
3. C.2-chloromethylpropane
4. D.1-chloro-2, 2-dimethylethane

Which of the following statements is TRUE of the complete hydrolysis of a glycerine by sodium hydroxide?

1. A.3 moles of NaOH are required for each mole of glyceride
2. B.3 moles of glycerol are produced.
3. C.Only one mole of soap is formed.
4. D.Concentrated H₂SO₄ is essential for the completion of the reaction.

Which of the following are the products of the reaction between CH₃COOH and Cl₂ in sunlight?

1. A.ClCH₂COOH + HCl
2. B.CH₃COCl + HOCl
3. C.CH₃COOCl + HCl
4. D.CH₃COCl + H₂O.