JAMB Chemistry 1990 past questions and answers

Which of the following is a physical change?

1. A.The bubbling of chlorine into water.
2. B.The bubbling of chlorine into a jar containing hydrogen
3. C.The dissolution of sodium chloride in water.
4. D.The passing of steam over heated iron

Changes in the physical states of a chemical substance T are shown in the scheme below.
The letters X, Y and Z respectively represent

1. A.sublimation, condensation and freezing
2. B.sublimation, vapourization and solidification
3. C.freezing, condensation and sublimation
4. D.evaporation, liquefaction and solidification

In the reaction: SnO₂ + 2C → Sn + 2CO, the mass of coke containing 80% carbon required to reduce 0.302 kg of pure tin oxide is [Sn = 119, O = 16, C = 12]

1. A.0.40 kg
2. B.0.20 kg
3. C.0.06 kg
4. D.0.04 kg

The Avogadro number of 24 g of magnesium is the same as that of

1. A.1g of hydrogen molecules
2. B.16 g of oxygen molecules
3. C.32 g of oxygen molecules
4. D.35.5 g of chlorine molecules.

If a gas occupies a container of volume 146 cm³ at 18°C and 0.971 atm, its volume in cm³ at s.t.p is

1. A.133
2. B.146
3. C.266
4. D.292

The volume occupied by 1.58 g of a gas at s.t.p is 500 cm³. What is the relative molecular mass of the gas? [G.M.V at s.t.p = 22.40 dm³].

1. A.28
2. B.32
3. C.44
4. D.71

Equal volumes of CO, SO₂, NO₂ and H₂S were released into a room at the same point and time. Which of the following gives the order of diffusion of the gases to the opposite corner of the room? [S = 32, C = 12, O = 16, N = 14, H = 1].

1. A.CO, SO₂, NO₂, H₂S
2. B.SO₂, NO₂, H₂S, CO
3. C.CO, H₂S, SO₂, NO₂
4. D.CO, H₂S, NO₂, SO₂

A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that

1. A.collisions are perfectly elastic
2. B.forces of repulsion exist
3. C.forces of repulsion and attraction are in equilibrium
4. D.collisions are inelastic.

Which of the following terms indicates the number of bonds that can be formed by an atom?

1. A.Oxidation number
2. B.Valence
3. C.Atomic number
4. D.Electronegativity

Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5. The relative abundance of the isotope of mass number 37 is

1. A.20
2. B.25
3. C.50
4. D.75

10.0 dm³ of air containing H₂S as an impurity was passed through a solution of Pb(NO₃)₂ until all the H₂S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO₃)₂ + H₂S → PbS + 2HNO₃ the percentage by volume of hydrogen sulphide in the air is [Pb = 207, S = 32, GMV at s.t.p = 22.4 dm³]

1. A.50.2
2. B.47.0
3. C.4.70
4. D.0.47

A blue solid, T, which weighed 5.0 g was placed on a table. After 8 hours, the resulting pink solid was found to weigh 5.5 g. It can be inferred that substance T

1. A.is deliquescent
2. B.is hydroscopic
3. C.has some molecules of water of crystallization
4. D.is efflorescent

The effluent of an industrial plant used in the electrolysis of concentrated brine, with a flowing mercury cathode may obtain impurities like

1. A.oxygen
2. B.hydrogen
3. C.mercury (II) chloride
4. D.hydrogen chloride.

The solubility in moles per dm³ of 20 g of CuSO₄ dissolved in 100 g of water at 180°C is [Cu = 63.5, S = 32, O = 16].

1. A.0.13
2. B.0.25
3. C.1.25
4. D.2.00

Smoke consists of

1. A.solid particles dispersed in liquid
2. B.solid or liquid particles dispersed in gas
3. C.gas or liquid particles dispersed in liquid
4. D.liquid particles dispersed in liquid.

Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9 g of sodium oxalate in 50 g of water at room temperature, calculate the minimum volume of 0.1 M calcium chloride required to produce maximum calcium oxalate using the above equation.

1. A.1.40 × 10² dm³
2. B.1.40 × 10² cm³
3. C.1.40 × 10⁻² dm⁻²
4. D.1.40 × 10⁻² cm³.

2.0 g of a monobasic acid was made up to 250 cm³ with distilled water. 25.00 cm³ of this solution required 20.00 cm³ of 0.1 M NaOH solution for complete neutralization. The molar mass of the acid is

1. A.200 g
2. B.160 g
3. C.100 g
4. D.50 g

What is the concentration of H⁺ ions in moles per dm³ of a solution of pH 4.398?

1. A.4.0 × 10⁻⁵
2. B.0.4 × 10⁻⁵
3. C.4.0 × 10⁻³
4. D.0.4 × 10⁻³

If 10.8 g of silver is deposited in a silver coulometer connected in series with a copper coulometer, the volume of oxygen liberated is [Ag = 108, Cu = 64, GMV at s.t.p = 22.40 dm³]

1. A.0.56 dm³
2. B.5.60 dm³
3. C.11.20 dm³
4. D.22.40 dm³

0.1 faraday of electricity deposited 2.95 g of nickel during electrolysis of an aqueous solution. Calculate the number of moles of nickel that will be deposited by 0.4 faraday. [Ni = 58.7]

1. A.0.20
2. B.0.30
3. C.0.04
4. D.5.87

Cr₂O₇²⁻ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ + 6Fe³⁺ + 7H₂O. In the above equation, the oxidation number of chromium changed from

1. A.+7 to +3
2. B.+6 to +3
3. C.+5 to +3
4. D.−2 to +3.

In the reaction IO₃⁻ + 5I⁻ + 6H⁺ → 3I₂ + 3H₂O, the oxidizing agent is

1. A.H⁺
2. B.I⁻
3. C.IO₃⁻
4. D.I₂.

Fe₂O_3(s) + 2Al_(s) → Al₂O_3(s) + 2Fe_(s). If the heats of formation of Al₂O₃ and Fe₂O₃ are −1670 kJ mol⁻¹ and −822 kJ mol⁻¹ respectively, the enthalpy change in kJ for the reaction is

1. A.+2492
2. B.+848
3. C.−848
4. D.−2492.

Iron galvanized with zinc is cathodically protected from corrosion. This is because

1. A.zinc has a more positive oxidation potential than iron
2. B.zinc has a less positive oxidation potential than iron
3. C.both have the same oxidation potential
4. D.zinc is harder than iron.

Which of the following samples will react fastest with dilute trioxonitrate (V) acid?

1. A.5 g of lumps of CaCO₃ at 25°C
2. B.5 g of powdered CaCO₃ at 25°C
3. C.5 g of lumps of CaCO₃ at 50°C
4. D.5g of powdered CaCO₃ at 50°C.

In the reaction 2HI_(g) ⇌ H_2(g) + I_2(g), ΔH = 10 kJ; the concentration of iodine in the equilibrium mixture can be increased by

1. A.raising the pressure
2. B.raising the temperature
3. C.adding a catalyst
4. D.lowering the pressure

Which of the following gases can be collected by the upward displacement of air?

1. A.NO
2. B.H₂
3. C.NH₃
4. D.Cl₂.

The brown fumes given off when trioxonitrate (V) acid is heated consist of

1. A.NO₂ and O₂
2. B.H₂O and NO₂
3. C.NO₂, O₂ and H₂O
4. D.NO, NO₂ and H₂O.

Which of the following tests will completely identify any one of sulphur (IV) oxide, hydrogen, carbon (IV) oxide and nitrogen (II) oxide?

1. A.Pass each gas into water and test with blue litmus paper.
2. B.Pass each gas into lime water
3. C.Expose each gas to atmospheric air
4. D.Pass each gas to concentrated tetraoxosulphate (VI) acid.

In the Haber process for the manufacture of ammonia, the catalyst commonly used is finely divided

1. A.vanadium
2. B.platinum
3. C.iron
4. D.copper

A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as

1. A.an acidic oxide
2. B.a basic oxide
3. C.a neutral oxide
4. D.an amphoteric oxide

Which of the following metals will liberate hydrogen from steam or dilute acid?

1. A.Copper
2. B.Iron
3. C.Lead
4. D.Mercury

Coal fire should not be used in poorly ventilated rooms because

1. A.of the accumulation of CO₂ which causes deep sleep
2. B.it is usually too hot
3. C.of the accumulation of CO which causes suffocation
4. D.it removes most of the gases in the rooms.

The major component of the slag from the production of iron is

1. A.an alloy of calcium and iron
2. B.coke
3. C.impure iron
4. D.calcium trioxosilicate (IV).

Sodium hydroxide should be stored in properly closed containers because it

1. A.readily absorbs water vapour from the air
2. B.is easily oxidized by atmospheric oxygen
3. C.turns golden yellow when exposed to light
4. D.melts at a low temperature

To make coloured glasses, small quantities of oxides of metals which form coloured silicates are often added to the reaction mixture consisting of Na₂CO₃ and SiO₂. Such a metal is

1. A.potassium
2. B.barium
3. C.zinc
4. D.copper

Which of the following compounds gives a yellow residue when heated and also reacts with aqueous sodium hydroxide to give a white gelatinous precipitate soluble in excess sodium hydroxide solution?

1. A.(NH₄)₂CO₃
2. B.ZnCO₃
3. C.Al₂(SO₄)₃
4. D.PbCO₃.

The structure of cis-2-butene is (see the structures in the figure)

1. A.CH₃—CH = CH—CH₃.
2. B.Structure B: CH₃ and H on each carbon of C=C, with both CH₃ groups on the same side
3. C.Structure C: CH₃ and H on each carbon of C=C, with the CH₃ groups on opposite sides
4. D.Structure D: CH₃ and H on one carbon of C=C, two CH₃ groups on the other

What is the IUPAC name for the hydrocarbon CH₃—C(CH₂CH₃) = CH—CH(CH₃)—CH₃? (structure in the figure)

1. A.2-ethyl-4-methylpent-2-ene
2. B.3,5-dimethylhex-3-ene
3. C.2, 4-dimethylhex-3-ene
4. D.2-methyl-4-ethylpent-3-ene.

CH₃—C ≡ CH (Na, liq NH₃) → P. Compound P, in the above reaction, is

1. A.CH₃—C(Na) = CH NH₂
2. B.CH₃—C(NH₂) = CH Na
3. C.CH₃—C ≡ C—Na
4. D.CH₃—C ≡ C—NH₂.

The label on a reagent bottle containing a clear organic liquid dropped off. The liquid was neutral to litmus and gave a colourless gas with metallic sodium. The liquid must be an

1. A.alkanoate
2. B.alkene
3. C.alkanol
4. D.alkane.

HOOC—COOH + NaOH → HOOC—COO⁻Na⁺ + H₂O
The above reaction is an example of

1. A.a displacement reaction
2. B.a neutralization reaction
3. C.an elimination reaction
4. D.saponification

Alkanoic acids have low volatility compared with alkanols because they

1. A.are more polar than alkanols
2. B.have two oxygen atoms while alkanols have one
3. C.form hydrogen bonds while alkanols do not
4. D.form two hydrogen bonds while alkanols form one.

The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2,2,4-trimethyl pentane and 45 g of n-heptane is

1. A.45
2. B.55
3. C.80
4. D.100.

Which of the following is formed when maltose reacts with concentrated tetraoxosulphate (VI) acid?

1. A.Carbon (IV) oxide
2. B.Coal tar
3. C.Charcoal
4. D.Toxic fumes.

Which of the following compounds represents the polymerization product of ethyne? (see the structures in the figure)

1. A.Ring A: six-membered ring with three alternating double bonds
2. B.Ring B: six-membered ring with two double bonds
3. C.Ring C: two fused six-membered rings
4. D.Ring D: six-membered ring with one double bond