JAMB Chemistry 1980 past questions and answers

In an attempt to remove sugar from a beaker containing a quantity of sand and sugar, 2 M ammonium chloride solution was accidentally added instead of water. Which of the following methods could be used to remove the ammonium chloride from the mixture?

1. A.Fractional distillation
2. B.Crystallization
3. C.Filtration followed by evaporation
4. D.Evaporation followed by sublimation
5. E.Filtration followed by sublimation.

The alloy duralumin is used for the building of aeroplanes because it

1. A.absorbs heat readily from the sun thereby preventing the inside of the plane from getting too cold at high attitudes
2. B.reflects sunlight readily, thereby keeping the inside of the plane cool
3. C.is extremely durable and possesses reflective ability
4. D.is easily the lightest building material
5. E.possesses both strength and lightness.

A solution X on mixing with AgNO₃ solution, gives a white precipitate soluble in NH₃. A solution Y, when added to X, also gives a white precipitate which is soluble on boiling. Solution Y contains

1. A.Ag⁺ion
2. B.Pb²⁺ion
3. C.Pb⁴⁺ ion
4. D.Zn²⁺ ion
5. E.Al³⁺ ion.

10cm³ of CO is mixed and sparked with 100 cm³ of air containing 21% O₂. If all the volumes are measured at S.T.P, the volume of resulting gases would be

1. A.90cm³
2. B.100 cm³
3. C.105 cm³
4. D.110 cm³
5. E.115 cm³.

A sample of an oxide of mercury weighed 1.00 g. When this was heated, oxygen was given off, and 1.00 g of mercury metal only was left. What is the formula of the oxide? (Hg = 200, O = 16)

1. A.Hg₂O
2. B.HgO₂
3. C.HgO₄
4. D.HgO
5. E.None of the above.

On heating, under suitable conditions, 1 litre of a monoatomic gas, X, combines with 1½ litres of oxygen to form an oxide. What is the formula of the oxide?

1. A.XO₃
2. B.X₂O₃
3. C.X₂O₂
4. D.XO₂
5. E.None of the above

If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water, and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be

1. A.2.2 M
2. B.1.1 M
3. C.0.22 M
4. D.0.11 M
5. E.0.20 M

1.0 g of CaCO₃ was treated with excess 0.1 M HCl. At the end of the reaction, the acid still left unreacted required 25 cm³ of 0.1 M Na₂CO₃ to neutralize it. What was the original volume of the acid? (Na = 23, Ca = 40, C = 12, O = 16, Cl = 35.5)

1. A.220 cm³
2. B.230cm³
3. C.240 cm³
4. D.250cm³
5. E.260cm³.

Which one of the following reactions is correct as written?

1. A.FeCl₂ + 3NH₄OH → Fe(OH)₃ + 3NH₄Cl.
2. B.Pb₂O₃ + 4HCl → PbCl₂ + 2H₂O.
3. C.PbNO₃ + H₂S → PbS + 2HNO₃
4. D.NaOH + H₂SO₄ → NaHSO₄ + H₂O.
5. E.2NH₄NO₃ → N₂ + 2H₂O.

How many grams of hydrogen gas will be liberated when 6 g of magnesium ribbon dissolves in 500 cm³ of 6 M HCl? (Mg = 24, H = 1, Cl = 35.5).

1. A.1.2 g
2. B.0.7 g
3. C.0.5 g
4. D.0.3 g
5. E.0.12 g

500cm³ oxygen was collected over water at 30°C and 752 mmHg pressure. What is the volume of dry oxygen at S.T.P? (Vapour pressure of water at 30°C = 32 mmHg).

1. A.475 cm³.
2. B.415cm³
3. C.586 cm³
4. D.500 cm³
5. E.427 cm³.

Which of the following statements is an exception in the assumptions of the kinetic theory of gases?

1. A.Gases are composed of many elastic particles
2. B.The particles are of negligible size
3. C.The particles are in constant random motion
4. D.The particles are of negligible mass
5. E.The particles collide with each other.

Which of the following statements is true?

1. A.Metals conduct electricity while non-metals do not
2. B.Metals have high density, non-metals have low density
3. C.Metals form basic oxides, non-metals form acidic oxides
4. D.In the electro chemical series, metals are above hydrogen while non-metals are below hydrogen
5. E.Metals lose electrons while non-metals gain electrons during normal reactions.

5.00 g of hydrated salt of barium when heated to a constant weight gave 4.26 g of anhydrous salt with a molecular weight of 208. The number of molecules of water of crystallization in the hydrated salt is

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

The boiling point of water is higher than that of methanol because

1. A.water is an oxide while methanol is an alcohol
2. B.inter-molecular forces in water are stronger than those in methanol
3. C.water is an inorganic compound while methanol is organic
4. D.water is an ionic compound while methanol is a covalent compound
5. E.water is more reactive than methanol

Chlorine, bromine and iodine resemble each other in that all

1. A.dissolve in alkalis
2. B.react violently with hydrogen without heating
3. C.displace each other from solutions of their salts
4. D.are gases
5. E.are liquids.

The following is an arrangement of elements in order of decreasing number of outer electrons; one of the elements is wrongly placed. Which is it? ALUMINIUM, CHLORINE, SILICON, MAGNESIUM AND SODIUM

1. A.Chlorine
2. B.Aluminium
3. C.Silicon
4. D.Magnesium
5. E.Sodium

Element X has a total of 19 electrons and can react with oxygen to form an oxide. Which of the following statements is NOT true of the oxide of the element?

1. A.When exposed to air, it slowly changes to liquid.
2. B.Its solution in water conducts electricity
3. C.Its solution in water, on evaporation, gives a white solid
4. D.Its solution in water liberates hydrogen when in contact with aluminium metal
5. E.Its oxide, when strongly heated, regenerates the element X.

Which ONE of the following statements is true?

1. A.All alkali metal salts dissolve with dissociation in water
2. B.Most ionic substances are easily vaporized.
3. C.Ionic substances exist only as liquids.
4. D.Non-ionic substances are good electrolytes
5. E.Nitrogen exists in a trivalent state in ammonium salts.

When ethene gas reacts with chlorine gas to form 1, 2-dichloroethene, the reaction is called

1. A.substitution
2. B.addition
3. C.polymerization
4. D.hydrolysis
5. E.reduction

20 cm³ of 1 M H₂SO₄ is mixed with 20 cm³ of 1 M NaOH. The resulting solution is

1. A.acidic with a molarity of 0.50 M H₂SO₄
2. B.acidic with a molarity of 0.25 M H₂SO₄
3. C.neutral
4. D.alkaline with a molarity of 0.25M NaOH
5. E.alkaline with a molarity of 0.50 M NaOH.

Which of the following is acceptable as the organic product of the reaction of ethanoic acid and ethanol with an acid catalyst?

1. A.Ethyl ethanoate
2. B.Methyl ethanoate
3. C.Ethyl methyl ketone
4. D.Butanol
5. E.None.

Air is passed through the apparatus shown (alkaline pyrogallol, then a U-tube of CaCl₂) and gas X comes out. In the above experiment X is

1. A.pure nitrogen
2. B.a mixture of nitrogen and oxygen
3. C.a mixture of nitrogen and carbondioxide
4. D.a mixture of oxygen and inert gases
5. E.a mixture of nitrogen and inert gases

Given the mean atomic mass of chlorine prepared in the laboratory to be 35.5 and assuming that chlorine contains two isotopes of mass number 35 and 37, what is the percentage composition of the isotope of mass number 35?

1. A.20
2. B.25
3. C.50
4. D.75
5. E.90

When dilute hydrochloric acid is added to iron(II) sulphide the gas evolved will

1. A.turn moist red litmus paper blue
2. B.turn lime water milky
3. C.blacken lead acetate paper
4. D.rekindle a glowing splint
5. E.burn with a squeaky pop.

In which of the following is the oxidation state of oxygen different from its value in water?

1. A.OH⁻
2. B.H₃O⁺
3. C.O⁻
4. D.H₂O₂
5. E.SO₂.

Which of the following silver halides is readily soluble in ammonium hydroxide?

1. A.AgI
2. B.AgBr
3. C.AgCl
4. D.AgF
5. E.None of the above.

The chemical reaction which takes place at the anode (positive electrode) in electrolysis is

1. A.oxidation
2. B.hydrolysis
3. C.dissociation
4. D.reduction
5. E.disproportionation

Which of the following does NOT happen when a zinc rod is introduced into a solution of copper (II) sulphate?

1. A.Electrons flow towards the zinc rod
2. B.The zinc rod dissolves
3. C.The temperature of the soil changes
4. D.The blue colour of the solution gradually disappears
5. E.Copper metal is deposited

Hardening of an oil may be achieved by

1. A.boiling the oil with water
2. B.boiling the oil with a catalyst
3. C.treating the oil with sodium hydroxide
4. D.treating the oil with hydrogen and catalyst
5. E.distilling the oil under reduced pressure.

A cold aqueous solution of sodium chloride is electrolysed using a graphite anode and an iron cathode. In the course of the electrolysis the electrolyte is continuously stirred. The liquid left after electrolysis will therefore consist of

1. A.sodium hydroxide solution
2. B.chlorine water
3. C.pure water
4. D.sodium hypochlorite solution
5. E.hydrochloric acid solution

When copper (II) sulphate solution is treated with excess ammonium hydroxide, a precipitate is first formed, and then this dissolves to give a deep blue solution. This deep blue solution is

1. A.Cu(OH)₂
2. B.CuSO₄.5H₂O
3. C.(NH₄)₂SO₄
4. D.Cu(NH₃)₄(OH)₂
5. E.CuSO₄.(NH₄)₂SO₄.2H₂O.

The IUPAC name for the compound CH₃–CH₂–C(CH₃) = C(CH₃)–CH₃ is

1. A.2, 3-dimethylpent-2, 3-ene
2. B.2, 3-dimethylpent-2-ene
3. C.3, 4-dimethylpent-3-ene
4. D.3, 4-dimethylpentene
5. E.3, 4-dimethylhept-2-ene.

Which of the following tests would confirm unequivocally that a solution X contains the sulphate ion if it gives with

1. A.silver nitrate solution, a white precipitate insoluble in dilute HNO₃
2. B.barium chloride solution, a white precipitate insoluble in dilute H₂SO₄
3. C.barium chloride solution, a white precipitate insoluble in dilute solution.
4. D.barium chloride solution a white precipitate soluble in dilute ammonia.
5. E.barium chloride solution a white precipitate insoluble in dilute HCl.

When chlorine gas is passed into a solution of sulphur dioxide

1. A.sulphur dioxide is reduced to sulphur
2. B.the chlorine is oxidized to hydrochloric acid
3. C.dilute sulphuric acid and hydrochloric acid are produced
4. D.hydrochloric acid and sulphur are produced
5. E.sulphur trioxide is the only product

A mixture of ethanol, sodium dichromate, and water is allowed to drop gradually into a boiling solution containing one part concentrated H₂SO₄ and three parts water, and the liberated gas is collected by cooling it with ice water to give a liquid. This liquid is

1. A.ethanoic acid
2. B.acetaldehyde
3. C.ethyl acetate
4. D.methanol
5. E.ethylene

Which of the following statements is false?

1. A.Acids react with some metals, liberating hydrogen.
2. B.Acids react with carbonates, liberating carbondioxide
3. C.Acids conduct electricity and are decomposed by the current, liberating hydrogen at the anode
4. D.Acids have a sour taste
5. E.Acids change the colour of indicators.

The best way of collecting chlorine is

1. A.by downward displacement of air
2. B.by upward displacement of air
3. C.over water
4. D.under water
5. E.over mercury

Cellulose and starches can be classified as one of the following

1. A.sugars
2. B.sucrose
3. C.hydrocarbons
4. D.carbohydrates
5. E.isomers

If one of the following oxides is heated with hydrogen or carbon using a bunsen burner, it is not reduced to the metal. Which one is it?

1. A.Lead oxide
2. B.Magnesium oxide
3. C.Copper oxide
4. D.Tin oxide
5. E.Iron oxide

Which of the following is the correct order in increasing boiling point, of the isomeric C₅H₁₂ compounds?

1. A.C–C–C–C–C < C–C(C)–C–C < C–C(C)(C)–C
2. B.C–C–C–C–C < C–C(C)(C)–C < C–C(C)–C–C
3. C.C–C(C)(C)–C < C–C–C–C–C < C–C(C)–C–C
4. D.C–C(C)(C)–C < C–C(C)–C–C < C–C–C–C–C
5. E.C–C(C)–C < C–C(C)(C)–C < C–C–C–C–C

Which of the following derivatives of nitrogen affords an aqueous solution having a pH of less than 7?

1. A.N₂O
2. B.NO
3. C.NO₂
4. D.NaNO₃
5. E.NH₃

Detergents are more advantageous than soaps in hard water districts because

1. A.on treatment with hard water they either form soluble calcium salts or do not react with calcium ions
2. B.on treatment with hard water they form soluble calcium salts
3. C.on treatment with hard water they form sodium salts
4. D.on treatment with hard water they are converted into soaps
5. E.on treatment with hard water they form more lather than soap does

Which of the following classes of organic compounds undergoes rapid oxidation with bromine water?

1. A.Alcohols
2. B.Alkenes
3. C.Carboxylic acids
4. D.Esters
5. E.Alkanes

The following graph demonstrates the rate of reaction between calcium carbonate (marble) and dilute hydrochloric acid. The graph shows that the rate of reaction is initially greatest when

1. A.the initial slope of the curve is steepest and this occur when small pieces of marble are used and is due to a small surface area of reactant
2. B.the initial slope of the curve is least steep and this occur when large pieces of marble are used and is due to a small surface area of reactant.
3. C.the initial slope of the curve is steepest and this occurs when small pieces of marble are used and is due to a large surface area of reactant
4. D.the initial slope of the curve is steepest and this occur when large pieces of marble are used and is due to a large surface area of reactant
5. E.the initial slope of the curve is least steep and this occur when small pieces of marble are used and is due to the increased surface area of the reactant.

An endothermic reaction is one during which heat is.........and can be represented by the symbol.......Which of the following combinations can be used accurately to complete the above definition?

1. A.liberated, -ΔH
2. B.liberated, +ΔH
3. C.absorbed, -ΔH
4. D.absorbed, + ΔH
5. E.absorbed, + ΔG.

The synthesis of sulphuric acid by the contact process employs the following equilibrium step as one of its stages: 2SO₂(g) + O₂ ⇌ 2SO₃(g) -ΔH. Which of the following conditions promotes the backward reaction?

1. A.Increased pressure and decreased temperature
2. B.Increased pressure, increased temperature and the presence of a catalyst
3. C.Decreased pressure, decreased concentration of oxygen and increased temperature
4. D.Decreased pressure, increased concentration of oxygen and increased temperature
5. E.Decreased pressure, decreased concentration of oxygen and decreased temperature.

Copper sulphate solution was electrolysed using the apparatus shown below. Which of the following changes are observed?

1. A.The bulb lights and copper is deposited at both electrodes
2. B.The bulb lights and copper is deposited at the anode and disappears from the cathode
3. C.The bulb lights and copper is deposited at the cathode and oxygen liberated at the anode
4. D.The bulb lights and copper is deposited at the cathode and disappears from the anode
5. E.The bulb lights but no additional changes are observed.