JAMB Chemistry 1983 past questions and answers

X is a crystalline salt of sodium. A solution of X in water turns litmus red and produces a gas which turns lime water milky when added to sodium carbonate. With barium chloride solution, X gives a white precipitate which is insoluble in dilute hydrochloric acid. X is

1. A.Na₂CO₃
2. B.NaHCO₃
3. C.NaHSO₄
4. D.Na₂SO₃
5. E.Na₂SO₄.

The alkanol obtained from the production of soap is

1. A.ethanol
2. B.glycerol
3. C.methanol
4. D.propanol
5. E.glycol

The flame used by welders in cutting metals is

1. A.butane gas flame
2. B.acetylene flame
3. C.kerosene flame
4. D.oxy-acetylene flame
5. E.oxygen flame

Consecutive members of an alkane homologous series differ by

1. A.CH
2. B.CH₂
3. C.CH₃
4. D.C_nH_n
5. E.C_nH_2n+2.

If an element has the electronic configuration 1s² 2s² 2p⁶ 3s² 3p⁴, it is

1. A.a metal
2. B.an alkaline earth metal
3. C.an s-block element
4. D.a p-block element
5. E.a transition element

Some copper (II) sulphate pentahydrate (CuSO₄.5H₂O), was heated at 120°C with the following results: Wt of crucible = 10.00 g; Wt of crucible + CuSO₄.5H₂O = 14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystallization were lost? [H = 1, Cu = 63.5, O = 16, S = 32]

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

The three-dimensional shape of methane is

1. A.hexagonal
2. B.trigonal
3. C.linear
4. D.tetrahedral
5. E.cubical

An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystalline solid, readily soluble in water. X contains the elements C, H, and O in the atomic ratio 1:2:1. The compound has a sweet taste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.
Compound W is

1. A.a soap
2. B.an oil
3. C.an alkane
4. D.an ester
5. E.sucrose

An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystalline solid, readily soluble in water. X contains the elements C, H, and O in the atomic ratio 1:2:1. The compound has a sweet taste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.
The molecular formula of X is

1. A.C₁₂H₂₂O₁₁
2. B.C₆H₁₂O₆
3. C.C₃H₆O₃
4. D.C₇H₁₄O₇
5. E.C₄H₆O₄

An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystalline solid, readily soluble in water. X contains the elements C, H, and O in the atomic ratio 1:2:1. The compound has a sweet taste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.
Reaction of X with yeast forms the basis of the

1. A.plastic industry
2. B.textile industry
3. C.brewing industry
4. D.soap industry
5. E.dyeing industry

A mixture of common salt, ammonium chloride and barium sulphate can best be separated by

1. A.addition of water followed by filtration then sublimation
2. B.addition of water followed by sublimation then filtration
3. C.sublimation followed by addition of water then filtration
4. D.fractional distillation
5. E.fractional crystallization

Which of the following relationships between the pressure P, the volume V and the temperature T, represents an ideal gas behaviour?

1. A.P α VT
2. B.P α T/V
3. C.PT α V
4. D.PV α 1/T
5. E.P α V/T

In the above experiment (Fig. 1) the litmus paper will initially

1. A.be bleached
2. B.turn green
3. C.turn red
4. D.turn blue
5. E.turn black

The colour imparted to a flame by calcium ion is

1. A.green
2. B.blue
3. C.brick-red
4. D.yellow
5. E.lilac

In the reaction M + N ⇌ P; ΔH = +Q kJ. Which of the following would increase the concentration of the product?

1. A.Decreasing the concentration of N
2. B.Increasing the concentration of P
3. C.Adding a suitable catalyst
4. D.Decreasing the temperature
5. E.Increasing the temperature

In which of the following processes is iron being oxidized?
1. Fe + H₂SO₄ → FeSO₄ + H₂
2. FeSO₄ + H₂S → FeS + H₂SO₄
3. 2FeCl₂ + Cl₂ → 2FeCl₃
4. 2FeCl₃ + SnCl₂ → 2FeCl₂ + SnCl₄.

1. A.1 only
2. B.2 only
3. C.3 only
4. D.1 and 3
5. E.2 and 4

In the above experiment (Fig. 2), a current was passed for 10 minutes and 0.63 g of copper was found to be deposited on the cathode of CuSO₄ cells. The weight of silver deposited on the cathode of AgNO₃ cell during the same period would be [Cu = 63, Ag = 108]

1. A.0.54 g
2. B.1.08 g
3. C.1.62g
4. D.2.16 g
5. E.3.24 g.

In the reaction Fe + Cu²⁺ → Fe²⁺ + Cu, iron displaces copper ions to form copper. This is due to the fact that

1. A.iron is in the metallic form while the copper is in the ionic form
2. B.the atomic weight of copper is greater than that of iron
3. C.copper metal has more electrons than iron metal
4. D.iron is an inert metal
5. E.iron is higher in the electrochemical series than copper.

C₂H₅—C(CH₃)=CH₂
The correct name of the compound with the above structural formula is

1. A.2-methylbutane
2. B.2-methylbut-2-ene
3. C.2-methylbut-1-ene
4. D.2-ethylprop-1-ene
5. E.2-ethylprop-2-ene

How many isomeric forms are there for the molecular formula C₃H₆Br₂?

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

A piece of burning sulphur will continue to burn in a gas jar of oxygen to give misty fumes which readily dissolve in water. The resulting liquid is

1. A.sulphur (VI) trioxide
2. B.tetraoxosulphate (VI) acid
3. C.trioxosulphate (IV) acid
4. D.dioxosulphate (II) acid
5. E.hydrogen sulphide

Sodium sulphate decahydrate (Na₂SO₄.10 H₂O) on exposure to air loses all its water of crystallization. The process of loss is known as

1. A.efflorescence
2. B.hygroscopy
3. C.deliquescence
4. D.effervescence
5. E.dehydration

Which of the following happens during the electrolysis of molten sodium chloride?

1. A.Sodium ion loses an electron
2. B.Chlorine atom gains an electron
3. C.Chlorine ion gains an electron
4. D.Sodium ion is oxidized
5. E.Chloride ion is oxidized.

Crude petroleum pollutant usually seen on some Nigerian creeks and waterways can be dispersed or removed by

1. A.heating the affected parts in order to boil off the petroleum
2. B.mechanically stirring to dissolve the petroleum in water
3. C.pouring organic solvents to dissolve the petroleum
4. D.spraying the water with detergents
5. E.cooling to freeze out the petroleum.

An element is electronegative if

1. A.it has a tendency to exist in the gaseous form
2. B.its ions dissolve readily in water
3. C.it has a tendency to lose electrons
4. D.it has a tendency to gain electrons
5. E.it readily forms covalent bonds.

Solutions X, Y, and Z have pH values 3.0, 5.0 and 9.0 respectively. Which of the following statements is correct?

1. A.All the solutions are acidic.
2. B.All the solutions are basic
3. C.Y and Z are more acidic than water
4. D.Y is more acidic than X.
5. E.Z is the least acidic

In the reactions
(I) H₂(g) + ½O₂(g) → H₂O(l); ΔH = −286 kJ
(II) C(s) + O₂(g) → CO₂(g); ΔH = −406 kJ
the equations imply that

1. A.more heat is absorbed in (I)
2. B.more heat is absorbed in (II)
3. C.less heat is evolved in (I)
4. D.reaction (II) proceeds faster than (I).
5. E.reaction (I) proceeds faster than (II).

Which of these metals, Mg, Fe, Pb and Cu will dissolve in dilute HCl?

1. A.All the metals.
2. B.Mg, Fe and Cu.
3. C.Mg, Fe and Pb
4. D.Mg and Fe only
5. E.Mg only.

Stainless steel is an alloy of

1. A.carbon, iron and lead
2. B.carbon, iron and chromium
3. C.carbon, iron and copper
4. D.carbon, iron and silver
5. E.carbon and iron only.

What volume of 0.5 M H₂SO₄ will exactly neutralize 20 cm³ of 0.1 M NaOH solution?

1. A.2.0 cm³
2. B.5.0 cm³
3. C.6.8 cm³
4. D.8.3 cm³
5. E.10.4 cm³

Which of the following pair of gases will NOT react further with oxygen at a temperature between 30°C and 400°C?

1. A.SO₂ and NH₃
2. B.CO₂ and H₂
3. C.NO₂ and SO₃
4. D.SO₃ and NO
5. E.CO and H₂.

Some metals are extracted from their ores after some preliminary treatments by electrolysis (L), some by thermal reaction (T) and some by a combination of both processes (TL). Which set-up in the following for the extraction of iron, copper and aluminium is correct?

1. A.Iron (L), copper (L), aluminium (T).
2. B.Iron (T), copper (L), aluminium (T).
3. C.Iron (TL), copper (TL), aluminium (TL).
4. D.Iron (L), copper (T), aluminium (T)
5. E.Iron (T), copper (L), aluminium (TL).

In the preparation of some pure crystals of Cu(NO₃)₂ starting with CuO, a student gave the following statements as steps he employed. Which of these shows a flaw in his report?

1. A.Some CuO was reacted with excess dilute H₂SO₄.
2. B.The solution was concentrated
3. C.When the concentrate was cooled, crystals formed were removed by filtration
4. D.The crystals were washed with very little cold water
5. E.The crystals were then allowed to dry.

Which of the following separation processes is most likely to yield high quality ethanol (>95%) from palm wine?

1. A.Fractional distillation without a dehydrant
2. B.Simple distillation with a dehydrant
3. C.Fractional distillation with a dehydrant
4. D.Column chromatography
5. E.Evaporation

Increasing the pressure of a gas

1. A.lowers the average kinetic energy of the molecules
2. B.decreases the density of the gas
3. C.decreases the temperature of the gas
4. D.increases the density of the gas
5. E.increases the volume of the gas

2.5 g of a hydrated barium salt gave on heating, 2.13 g of the anhydrous salt. Given that the relative molecular mass of the anhydrous salt is 208, the number of molecules of water of crystallization of the barium salt is

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

3.06 g of a sample of potassium trioxochlorate (V) (KClO₃) was required to make a saturated solution with 10cm³ of water at 25°C. The solubility of the salt at 25°C is [K = 39, Cl = 35.5, O = 16]

1. A.5.0 moles dm⁻³
2. B.3.0 moles dm⁻³
3. C.2.5 moles dm⁻³
4. D.1.0 moles dm⁻³
5. E.0.5 moles dm⁻³.

The cracking process is very important in the petroleum industry because it

1. A.gives purer products
2. B.yields more lubricants
3. C.yields more engine fuels
4. D.yields more asphalt
5. E.yields more candle wax

A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is

1. A.O₂
2. B.NO
3. C.SO₂
4. D.NH₃
5. E.CO₂

Which of the following solutions will give a white precipitate with barium chloride solution and a green flame test?

1. A.Na₂SO₄
2. B.CuSO₄
3. C.CaSO₄
4. D.CaCl₂
5. E.(NH₄)₂SO₄.

The mass of an atom is determined by

1. A.its ionization potential
2. B.its electrochemical potential
3. C.the number of protons and electrons
4. D.the number of neutrons and protons
5. E.the number of neutrons and electrons

Which of the following is a neutralization reaction?

1. A.Addition of sodium chloride solution to potassium chloride solution
2. B.Addition of trioxonitrate (V) acid (nitric acid) to distilled water.
3. C.Addition of trioxonitrate (V) acid (nitric acid) to tetraoxosulphate (VI) acid (sulphuric acid).
4. D.Addition of trioxonitrate (V) acid (nitric acid) to potassium trioxonitrate (V) (potassium nitrate) solution
5. E.Addition of trioxonitrate (V) acid (nitric acid) to potassium hydroxide solution.

A jet plane carrying 3,000 kg of ethane burns off all the gas, forming water and carbondioxide. If all the carbondioxide is expelled and all the water formed is condensed and kept on board the plane, then the gain in weight is

1. A.1,800 kg
2. B.900 kg
3. C.600 kg
4. D.2,400 kg
5. E.1,200 kg

Liquid X, reacts with sodium trioxocarbonate (IV) (Na₂CO₃) to give a gas which turns calcium chloride solution milky. X is

1. A.Na₂SO₄(aq)
2. B.KI(aq)
3. C.an alkali
4. D.an acid
5. E.a hydrocarbon

Which of the following statements is FALSE?

1. A.Copper (II) ion can be reduced to copper (I) ion by hydrochloric acid and zinc.
2. B.Sodium metal dissolves in water giving oxygen
3. C.Nitrogen is insoluble in water
4. D.Carbondioxide is soluble in water
5. E.Lead has a higher atomic weight than copper

When sodium dioxonitrate (III) (NaNO₂) dissolves in water, ΔH is positive. The process of dissolution is

1. A.exothermic
2. B.endothermic
3. C.isothermal
4. D.isomeric
5. E.hygroscopic

The equilibrium reaction between copper (I) chloride and chlorine at 25°C and 1 atmosphere is represented by the equation: 2CuCl + Cl₂ ⇌ 2CuCl₂, ΔH = −166 kJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

1. A.more CuCl₂ is formed at 40°C.
2. B.More CuCl₂ is formed at 10°C.
3. C.Less CuCl₂ is formed at 10°C.
4. D.There is no change in the amount of CuCl₂ formed at 40°C and 10°C.
5. E.More CuCl is consumed at 40°C.

Zn + 2HCl → ZnCl₂ + H₂
The rate of the above reaction will be greatly increased if

1. A.the zinc is in the powdered form
2. B.a greater volume of the acid is used
3. C.a smaller volume of the acid is used
4. D.the reaction vessel is immersed in an ice-bath
5. E.the zinc is in the form of pellets.

Zn + H₂SO₄ → ZnSO₄ + H₂.
In the above reaction how much zinc will be left undissolved if 2.00 g of zinc is treated with 10 cm³ of 1.0 M of H₂SO₄? [Zn = 65, S = 32, O = 16, H = 1]

1. A.1.35 g
2. B.1.00 g
3. C.0.70 g
4. D.0.65 g
5. E.0.00 g

30 cm³ of 0.1 M Al(NO₃)₃ solution is reacted with 100cm³ of 0.15M of NaOH solution. Which reactant is in excess, and by how much?

1. A.NaOH solution, by 70 cm³
2. B.NaOH solution, by 60 cm³
3. C.NaOH solution, by 40 cm³
4. D.Al(NO₃)₃ solution, by 20 cm³
5. E.Al(NO₃)₃ solution, by 10 cm³.