JAMB Chemistry 1989 past questions and answers

Which of the following would support the conclusion that a solid sample is a mixture?

1. A.The solid can be ground to a fine powder.
2. B.The density of the solid is 2.25 g dm³.
3. C.The solid has a melting range of 300°C to 375°C.
4. D.The solid absorbs moisture from the atmosphere

The molar ratio of carbon to hydrogen of a volatile liquid compound is 1:2. 0.12 g of the liquid on evaporation at s.t.p. gave 32 cm³ of vapour. The molecular formula of the liquid is [G.M.V = 22.4 dm³, C = 12, H = 1]

1. A.C₃H₆
2. B.C₄H₈
3. C.C₅C₁₀
4. D.C₆H₁₂

From the vapour pressure curves of liquids I, II and III shown, it can be deduced that

1. A.liquid I has the highest boiling point
2. B.liquid II has the highest boiling point
3. C.liquid III has the highest boiling point
4. D.liquid III has the lowest boiling point.

20.00 cm³ of a solution containing 0.53 g of anhydrous Na₂CO₃ in 100 cm³ requires 25.00 cm³ of H₂SO₄ for complete neutralisation. The concentration of the acid solution in moles per dm³ is [H = 1, C = 12, O = 16, Na = 23, S = 32]

1. A.0.02
2. B.0.04
3. C.0.06
4. D.0.08

The minimum volume of oxygen required for the complete combustion of a mixture of 10 cm³ of CO and 15 cm³ of H₂ is

1. A.25.0 cm³
2. B.12.5 cm³
3. C.10.0 cm³
4. D.5.0 cm³.

What is the partial pressure of hydrogen gas collected over water at standard atmospheric pressure and 25°C if the saturation vapour pressure of water is 23 mm Hg at that temperature?

1. A.737 mm Hg
2. B.763 mm Hg
3. C.777 mm Hg
4. D.783 mm Hg.

The atomic radius of Li, Na and K are 1.33A, 1.54A and 1.96A respectively. Which of the following explains this gradation in atomic radius?

1. A.Electropositivity decreases from Li to Na to K
2. B.Electronegativity decreases from Li to Na to K.
3. C.The number of electron shells increases from Li to Na to K.
4. D.The elements are in the same period.

Which of the curves W, X, Y and Z in the graph of PV/RT against P illustrates the behaviour of an ideal gas?

1. A.W
2. B.X
3. C.Y
4. D.Z

Elements X and Y have electronic configurations 1s²2s²2p⁴ and 1s²2s²2p⁶3s²3p¹ respectively. When they combine, the formula of the compound formed is

1. A.XY
2. B.YX
3. C.X₂Y₃
4. D.Y₂X₃.

The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains

1. A.78 protons and 55 electrons
2. B.55 protons and 78 neutrons
3. C.55 protons and 78 electrons
4. D.78 protons and 55 neutrons.

Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is a noble gas?

1. A.P
2. B.Q
3. C.R
4. D.S

How many valence electrons are contained in the element represented by ³¹₁₅P?

1. A.3
2. B.5
3. C.15
4. D.31

The gaseous pollutant sulphur (IV) oxide is most likely to be detected in fairly reasonable quantities in the area around a plant for the

1. A.extraction of aluminium from bauxite
2. B.production of margarine
3. C.smelting of copper
4. D.production of chlorine from brine.

A hydrated salt of formula MSO₄.xH₂O contains 45.3% by mass of water of crystallisation. Calculate the value of x. [M = 56, S = 32, O = 16, H = 1]

1. A.3
2. B.5
3. C.7
4. D.10

Using 50 cm³ of 1 M potassium hydroxide and 100 cm³ of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm³ of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV). [K = 39, S = 32, O = 16, H = 1]

1. A.50,50
2. B.25,50
3. C.50,25
4. D.25,25

A solution of calcium bromide contains 20 g dm⁻³. What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80]

1. A.0.1, 0.1
2. B.0.1, 0.2
3. C.0.1, 0.05
4. D.0.05, 0.1

The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as

1. A.an allotropic oxide
2. B.an amphoteric oxide
3. C.a peroxide
4. D.a dioxide

An acid and its conjugate base

1. A.can neutralise each other to form a salt
2. B.differ only by a proton
3. C.differ only by the opposite charges they carry
4. D.are always neutral substances

The same current is passed for the same time through solutions of AgNO₃ and CuSO₄ connected in series. How much silver will be deposited if 1.0 g of copper is produced? [Cu = 63.5, S = 32, O = 16, Ag = 108, N = 14]

1. A.1.7 g
2. B.3.4 g
3. C.6.8 g
4. D.13.6 g

What is discharged at the cathode during the electrolysis of copper (II) tetraoxosulphate (VI) solution?

1. A.Cu²⁺ only
2. B.H⁺ only
3. C.Cu²⁺ and H⁺
4. D.Cu²⁺ and SO₄²⁻

An element, Z forms an anion whose formula is [Z(CN)₆]^y. If Z has an oxidation number of +2, what is the value of y?

1. A.−2
2. B.−3
3. C.−4
4. D.−5

Which of the reactions below is NOT an example of a redox reaction?
I Fe + 2Ag⁺ → Fe²⁺ + 2Ag
II 2H₂S + SO₂ → 2H₂O + 3S
III N₂ + O₂ ⇌ 2NO
IV CaCO₃ → CaO + CO₂

1. A.I, II and III
2. B.II and III
3. C.III and IV
4. D.IV only

The combustion of ethene, C₂H₄, is given by the equation C₂H₄ + 3O₂ → 2CO₂ + 2H₂O; ΔH = −1428 kJ. If the molar heats of formation of water and carbon (IV) oxide are −286 kJ and −396 kJ respectively, calculate the molar heat of formation of ethene in kJ

1. A.−2792
2. B.+2792
3. C.−64
4. D.+64

CO_(g) + H₂O_(g) ⇌ CO_2(g) + H_2(g), ΔH = −41000 J. Which of the following factors favour the formation of hydrogen in the above reaction?
I. high pressure II. low pressure III. High temperature IV. Use of excess steam

1. A.I, III and IV
2. B.III only
3. C.II, III and I
4. D.IV only

The graph shows a typical heating curve from the solid phase through the liquid phase to the gaseous phase of a substance. Which part of the curve shows solid and liquid in equilibrium?

1. A.T
2. B.U
3. C.X
4. D.Y

Which of the following represents the balanced equation for the reaction of copper with concentrated trioxonitrate (V) acid?

1. A.Cu_(s) + 2HNO_3(aq) → Cu(NO₃)_2(aq) + H_2(g)
2. B.Cu_(s) + 4HNO_3(aq) → Cu(NO₃)_2(aq) + 2H₂O_(l) + 2NO_2(g)
3. C.3Cu_(s) + 8HNO_3(aq) → 3Cu(NO₃)_2(aq) + 4H₂O_(l) + 2NO_(g)
4. D.3Cu_(s) + 4HNO_3(aq) → 3Cu(NO₃)_2(aq) + 2H₂O_(l) + 2NO_(g).

The catalyst used in the contact process for the manufacture of tetraoxosulphate (VI) acid is

1. A.manganese (IV) oxide
2. B.manganese (II) tetraoxosulphate (VI)
3. C.vanadium (V) oxide
4. D.iron metal.

Some products of destructive distillation of coal are

1. A.carbon (IV) oxide and ethanoic acid
2. B.trioxocarbonate (IV) acid and methanoic acid
3. C.producer gas and water gas
4. D.coke and ammonia liquor.

Gunpowder is made from charcoal, sulphur and potassium trioxonitrate (V). The salt in the mixture performs the function of

1. A.an oxidant
2. B.a reductant
3. C.a solvent
4. D.a catalyst

Which of the following reactions is (are) feasible?
I Br_2(l) + 2Cl⁻_(aq) → 2Br⁻_(aq) + Cl_2(g)
II 2I⁻_(aq) + Br_2(l) → 2Br⁻_(aq) + I_2(s)
III 2F⁻_(aq) + Cl_2(g) → 2Cl⁻_(aq) + F_2(g)
IV 2F⁻_(aq) + Br_2(l) → 2Br⁻_(aq) + F_2(g)

1. A.I
2. B.II
3. C.I and III
4. D.III and IV

Bleaching powder, CaOCl₂.H₂O, deteriorates on exposure to air because

1. A.it loses its water of crystallization
2. B.atmospheric nitrogen displaces chlorine from it
3. C.carbon (IV) oxide of the atmosphere displaces chlorine from it
4. D.bleaching agents should be stored in solution.

The products of the thermal decomposition of ammonium trioxonitrate (V) are

1. A.NO₂ and oxygen
2. B.NH₃ and oxygen
3. C.nitrogen and water
4. D.N₂O and water.

The scale of a chemical balance is made of iron plate and coated with copper electrolytically because

1. A.iron is less susceptible to corrosion than copper
2. B.copper is twice as susceptible to corrosion as iron
3. C.copper is less susceptible to corrosion than iron
4. D.copper and iron are equally susceptible to corrosion

A metal is extracted from its ore by the electrolysis of its molten chloride and it displaces lead from lead (II) trioxonitrate (V) solution. The metal is

1. A.copper
2. B.aluminium
3. C.zinc
4. D.sodium

Mortar is NOT used for under-water construction because

1. A.it hardens by loss of water
2. B.its hardening does not depend upon evaporation
3. C.it requires concrete to harden
4. D.it will be washed away by the flow of water.

Which of the following is NOT involved in the extraction of metals from their ores?

1. A.Reduction with carbon
2. B.Reduction with other metals
3. C.Reduction by electrolysis
4. D.Oxidation with oxidizing agents

Which of the following compounds is an isomer of the compound CH₃–CH₂–CH(CH₃)–CH₂–CH₃?

1. A.CH₃–CH₂–CH(CH₂CH₃)–CH₂–CH₃
2. B.CH₃–CH₂–CH(CH₂CH₃)–CH₃
3. C.CH₃–CH₂–CH(CH₃)–CH₃
4. D.CH₃–CH(CH₃)–CH₂–CH₂–CH₃

When excess chlorine is mixed with ethene at room temperature, the product is

1. A.1,2–dichloroethane
2. B.1,2–dichloroethene
3. C.1,1–dichloroethane
4. D.1, 1–dichloroethene.

Vulcanization of rubber is a process by which

1. A.isoprene units are joined to produce rubber
2. B.rubber latex is coagulated
3. C.sulphur is chemically combined in the rubber
4. D.water is removed from the rubber.

The reaction between ethanoic acid and sodium hydroxide is an example of

1. A.esterification
2. B.neutralization
3. C.hydroxylation
4. D.hydrolysis

The bond which joins two ethanoic acid molecules in the liquid state is

1. A.a covalent bond
2. B.an ionic bond
3. C.a dative covalent bond
4. D.a hydrogen bond.

The alkaline hydrolysis of fats and oils produces soap and

1. A.propane 1, 1, 3-triol
2. B.propane-1,3,3-triol
3. C.propane-1,2,2-triol
4. D.propane-1,2,3-triol

Which of the following is NOT a monomer?

1. A.C₆H₆ (benzene)
2. B.CH₂ = CH₂
3. C.CH₂ = CHCl
4. D.C₆H₅CH = CH₂ (phenylethene)

What is the IUPAC name for the compound CH₂ = C(CH₃)CH₂Cl?

1. A.1-chloro-2-methylprop-2, 3-ene
2. B.1-chloro-2-methylprop-2-ene
3. C.3-chloro-2-methylprop-1-ene
4. D.3-chloro-2-methylprop-1, 2-ene.

The gas responsible for most of the fatal explosions in coal mines is

1. A.butane
2. B.ethene
3. C.ethane
4. D.methane

Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature?

1. A.X and Z
2. B.Y
3. C.X
4. D.Z