JAMB Chemistry 2002 past questions and answers

A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound? [K = 39, Cl = 35.5, O = 16]

1. A.KClO₄
2. B.KClO
3. C.KClO₂
4. D.KClO₃

The formula CH₂O for ethanoic acid is regarded as its

1. A.molecular formula
2. B.general formula
3. C.empirical formula
4. D.structural formula

The chromatographic separation of ink is based on the ability of the components to

1. A.react with the solvent
2. B.react with each other
3. C.dissolve in each other in the column
4. D.move at different speeds in the column.

Which of the following gases contains the least number of atoms at s.t.p.?

1. A.1 mole of butane
2. B.3 moles of ozone
3. C.4 moles of chlorine
4. D.7 moles of argon

In the reaction E + F ⇌ G + H, the backward reaction is favoured if the concentration of

1. A.F is increased
2. B.E is increased
3. C.E is reduced
4. D.G is reduced.

In the diagram above, the curve that represents the production of oxygen gas from the decomposition of KClO₃ in the presence of MnO₂ catalyst is

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

Which of the following equations shows that a reaction is in equilibrium?

1. A.ΔG < 0
2. B.ΔG = ΔH − TΔS
3. C.ΔG > 0
4. D.ΔG = 0

PCl_5(g) ⇌ PCl_3(g) + Cl_2(g)
In the reaction above, a decrease in pressure will

1. A.decelerate the reaction
2. B.increase the yield of PCl₃
3. C.increase the yield of PCl₅
4. D.accelerate the reaction.

When H₂S is passed into a solution of iron (III) chloride, the solution turns

1. A.pale green
2. B.pale red
3. C.brown
4. D.colourless.

The Arrhenius equation expresses the relationship between the speed of a reaction and its

1. A.molecular collisions
2. B.heat of reaction
3. C.catalyst
4. D.activation energy

When dissolved in water, NaOH flakes show

1. A.an endothermic change
2. B.an exothermic change
3. C.a slow reaction
4. D.a rapid reaction.

Cu₂S_(s) + O_2(g) → 2Cu_(s) + SO_2(g)
What is the change in the oxidation number of copper in the reaction above?

1. A.+1 to 0
2. B.0 to +2
3. C.+2 to +1
4. D.0 to +1

The products of the electrolysis of dilute sodium hydroxide using platinum electrodes are

1. A.hydrogen and oxygen gases
2. B.water and hydrogen gas
3. C.water and sodium metal
4. D.sodium metal and oxygen gas.

The solubility of a salt of molar mass 101g at 20°C is 0.34 mol dm⁻³. If 3.40g of the salt is dissolved completely in 250cm³ of water in a beaker, the resulting solution is

1. A.a suspension
2. B.saturated
3. C.unsaturated
4. D.supersaturated

Tetraoxosulphate (VI) acid burns the skin by

1. A.hydrolysis
2. B.hydration
3. C.heating
4. D.dehydration

When a salt loses its water of crystallization to the atmosphere on exposure, the process is said to be

1. A.efflorescence
2. B.deliquescence
3. C.effervescence
4. D.fluorescence.

Three drops of a 1.0mol dm⁻³ solution of NaOH are added to 20cm³ of a solution of pH 8.4. The pH of the resulting solution will be

1. A.close to that of pure water
2. B.unaltered
3. C.greater than 8.4
4. D.less than 8.4

25cm³ of a 0.2 mol dm⁻³ solution of Na₂CO₃ requires 20cm³ of a solution of HCl for neutralization. The concentration of the HCl solution is

1. A.0.5 mol dm⁻³
2. B.0.6 mol dm⁻³
3. C.0.2 mol dm⁻³
4. D.0.4 mol dm⁻³

The substance least considered as a source of environmental pollution is

1. A.lead compounds
2. B.organophosphorous compounds
3. C.silicate minerals
4. D.uranium.

The furring of kettles is caused by the presence in water of

1. A.calcium tetraoxosulphate (VI)
2. B.calcium hydrogentrioxocarbonate (IV)
3. C.calcium hydroxide
4. D.calcium trioxocarbonate (IV).

Which of the following solutions containing only hydroxyl ions will liberate hydrogen gas when reacted with magnesium metal?

1. A.1.0 × 10⁻⁶ mol dm⁻³
2. B.1.0 × 10⁻¹² mol dm⁻³
3. C.1.0 × 10⁻² mol dm⁻³
4. D.1.0 × 10⁻⁴ mol dm⁻³

The property which makes alcohol soluble in water is the

1. A.boiling point
2. B.hydrogen bonding
3. C.ionic character
4. D.covalent nature.

Steam changes the colour of anhydrous cobalt (II) chloride from

1. A.blue to pink
2. B.white to red
3. C.white to green
4. D.blue to white

The gas that gives brown colouration in brown ring test is

1. A.NO
2. B.CO₂
3. C.NO₂
4. D.CO

Ethanol can easily be produced by

1. A.fermentation of starch
2. B.distillation of starch solution
3. C.catalytic oxidation of methane
4. D.destructive distillation of wood.

Which of the following gives a precipitate when treated with NaOH solution?

1. A.AlCl₃
2. B.NH₄Cl
3. C.CH₃COONa
4. D.Na₂CO₃.

An example of element that can catenate is

1. A.bromine
2. B.nitrogen
3. C.chlorine
4. D.carbon

The reaction of an alkene with hydrogen in the presence of a catalyst is

1. A.a substitution reaction
2. B.an oxidation reaction
3. C.a nucleophilic reaction
4. D.an addition reaction.

The number of isomers formed by C₆H₁₄ is

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

Which of these pairs are synthetic and natural macromolecules respectively?

1. A.Haemoglobin and nylon, creatine and polyethylene.
2. B.Nylon and polyethylene, creatine and haemoglobin
3. C.Nylon and creatine, polyethylene and haemoglobin
4. D.Polyethylene and creatine, nylon and haemoglobin.

Ordinary glass is manufactured from silica, CaCO₃ and

1. A.Na₂CO₃
2. B.K₂CO₃
3. C.K₂SO₄
4. D.NaHCO₃

A red precipitate of copper (I) carbide is formed when ammonium solution of copper (I) chloride is introduced into

1. A.CH₃CH₂CH₂CH₃
2. B.CH₂=CH−CH₂CH₃
3. C.CH₃CH₂−C≡CH
4. D.CH₃−C≡C−CH₃

CH₃CH₂−CH(CH₃)−OH
The compound above is

1. A.glycol
2. B.primary alkanol
3. C.secondary alkanol
4. D.tertiary alkanol

The boiling of fat and aqueous caustic soda is referred to as

1. A.hydrolysis
2. B.esterification
3. C.acidification
4. D.saponification

The most important use of hydrogen is in the

1. A.manufacture of ammonia
2. B.manufacture of methyl alcohol
3. C.manufacture of ethyl alcohol
4. D.hydrogenation of oils.

Hydrogen is readily released when dilute hydrochloric acid reacts with

1. A.Cu
2. B.Na
3. C.Au
4. D.Ag

The intermediate product formed when ethanol is progressively oxidized to ethanoic acid with potassium heptaoxodichromate (VI) is

1. A.butanal
2. B.ethanal
3. C.methanal
4. D.propanal

A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The rock sample contains

1. A.Cl⁻
2. B.NO₃⁻
3. C.SO₃²⁻
4. D.SO₄²⁻

Which of the following statements is true of a proton?

1. A.The mass of a proton is 1840 times the mass of an electron
2. B.The total mass of the protons in a particular nucleus is always half the nuclear mass.
3. C.The mass of a proton is one-twelfth the molar mass of carbon
4. D.The mass of a proton is 1.0008g.

Which of the following chlorides would exhibit the least ionic character?

1. A.MgCl₂
2. B.CaCl₂
3. C.LiCl
4. D.AlCl₃

A fixed mass of gas has a volume of 92cm³ at 3°C. What will be its volume at 18°C if the pressure remains constant?

1. A.15.3cm³
2. B.87.3cm³
3. C.552.0cm³
4. D.97.0cm³

The processes which return carbon (IV) oxide to the atmosphere include

1. A.respiration,decay and combustion
2. B.photosynthesis, respiration and transpiration
3. C.ozone depletion, combustion and decay
4. D.photosynthesis, decay and respiration.

The postulate of Dalton's atomic theory which still holds is that

1. A.atoms can neither be created nor destroyed
2. B.the particles of the same element are exactly alike
3. C.particles of different elements combine in a simple whole number ratio
4. D.all elements are made of small indivisible particles.

A gas X diffuses twice as fast as gas Y under the same conditions. If the relative molecular mass of X is 28, calculate the relative molecular mass of Y.

1. A.112
2. B.120
3. C.56
4. D.14

¹⁴₆C → X + β
X in the equation above represents

1. A.¹²₆C
2. B.¹²₅B
3. C.¹⁴₇N
4. D.¹³₆C

If 0.75 mole of cyclopropane and 0.66 mole of oxygen are mixed in a vessel with a total pressure of 0.7 atmosphere, what is the partial pressure of oxygen in the mixture?

1. A.0.44 atmosphere
2. B.0.22 atmosphere
3. C.0.55 atmosphere
4. D.0.33 atmosphere