JAMB Chemistry 1988 past questions and answers

In the experiment shown in the figure, solid ammonium chloride is heated at the closed end of a tube. Ammonium chloride crystals deposit on the walls of the tube as a result of

1. A.evaporation
2. B.recrystallization
3. C.sublimation
4. D.fractional precipitation.

The formula of the compound formed in a reaction between a trivalent metal M and a tetravalent non-metal X is

1. A.MX
2. B.M₃X₄
3. C.M₄X₃
4. D.M₃X₂.

2.25 g of a sample of an oxide of copper on reduction gave 2.0 g of copper. 2.50 g of another oxide of copper on reduction also gave 2.0 g of copper. These results are in accordance with the law of

1. A.constant composition
2. B.conservation of matter
3. C.multiple proportions
4. D.definite proportions.

One mole of propane is mixed with five moles of oxygen. The mixture is ignited and the propane burns completely. What is the volume of the products at s.t.p? [G.M.V = 22.4 dm³ mol⁻¹]

1. A.112.0 dm³
2. B.67.2 dm³
3. C.56.0 dm³
4. D.44.8 dm³.

9.0 dm³ of a gas at s.t.p was subjected by means of a movable piston to two times the original pressure with the temperature being now kept at 364 K. What is the volume of the gas in dm³ at this pressure?

1. A.2.0
2. B.4.5
3. C.6.0
4. D.8.3

Which of the gas laws does the graph of volume against temperature (Kelvin) shown illustrate?

1. A.Boyle
2. B.Charles
3. C.Graham
4. D.Gay-Lussac.

An increase in temperature causes an increase in the pressure of a gas because there is an increase in the

1. A.average velocity of the molecules
2. B.number of collisions between the molecules
3. C.density of the molecules
4. D.free mean path between each molecule and the other.

The forces holding naphthalene crystals together can be overcome when naphthalene is heated to a temperature of 354 K resulting in the crystals melting. These forces are known as

1. A.coulombic
2. B.ionic
3. C.covalent
4. D.Van der Waals

A metallic ion X²⁺ with an inert gas structure contains 18 electrons. How many protons are there in this ion?

1. A.20
2. B.18
3. C.16
4. D.2

Which of the following physical properties decreases across the Periodic Table?

1. A.Ionization potential
2. B.Electron affinity
3. C.Electronegativity
4. D.Atomic radius

What are the possible oxidation numbers for an element if its atomic number is 17?

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

The energy change accompanying the addition of an electron to a gaseous atom is called

1. A.first ionization energy
2. B.second ionization energy
3. C.electron affinity
4. D.electronegativity

The molar ratio of oxygen to nitrogen in dissolved air is 2:1 whereas the ratio is 4:1 in atmospheric air because

1. A.nitrogen is less soluble than oxygen
2. B.oxygen is heavier than nitrogen
3. C.nitrogen has a higher partial pressure in air
4. D.gases are hydrated in water.

1.34 g of hydrated sodium tetraoxosulphate (VI) was heated to give an anhydrous salt weighing 0.71 g. The formula of the hydrated salt is [Na = 23, S = 32, O = 16, H = 1]

1. A.Na₂SO₄.7H₂O
2. B.Na₂SO₄.3H₂O
3. C.Na₂SO₄.2H₂O
4. D.Na₂SO₄.H₂O

The ion that may be assumed to have negligible concentration in a sample of water that lathers readily with soap is

1. A.Mg²⁺
2. B.K⁺
3. C.CO₃²⁻
4. D.HCO₃⁻

A substance S is isomorphous with another substance R. When a tiny crystal of S is added into a supersaturated solution of R,

1. A.S dissolves in the solution
2. B.crystals of R are precipitated
3. C.there is no observable change
4. D.R and S react to generate heat

Which of the following dilute solutions has the lowest pH value?

1. A.Calcium trioxocarbonate (IV)
2. B.Sodium trioxocarbonate (IV)
3. C.Hydrochloric acid
4. D.Ethanoic acid.

Which of the following in aqueous solution is neutral to litmus?

1. A.NH₄Cl
2. B.Na₂CO₃
3. C.FeCl₃
4. D.NaCl

What volume of a 0.1 M H₃PO₄ will be required to neutralize 45.0 cm³ of a 0.2 M NaOH?

1. A.10.0 cm³
2. B.20.0 cm³
3. C.27.0 cm³
4. D.30.0 cm³

Which of the following substances is a basic salt?

1. A.Na₂CO₃
2. B.Mg(OH)Cl
3. C.NaHCO₃
4. D.K₂SO₄.Al₂(SO₄)₃.24H₂O

Which of the following acts both as a reducing and an oxidizing agent?

1. A.H₂
2. B.SO₂
3. C.H₂S
4. D.C

Which of the following reactions takes place in the cathode compartment during the electrolysis of copper (II) chloride solution?

1. A.Cu²⁺_(aq) + 2e⁻ → Cu(s)
2. B.2Cl⁻ − 2e⁻ → Cl₂
3. C.Cu_(s) − 2e⁻ → Cu²⁺_(aq)
4. D.Cu²⁺_(aq) + 2Cl⁻(aq) → CuCl_2(aq).

The mass of a substance, M, liberated at an electrode during electrolysis is proportional to the quantity of electricity, Q passing through the electrolyte. This is represented graphically by (see the graphs A–D in the figure)

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

A mixture of starch solution and potassium iodide was placed in a test tube. On adding dilute tetraoxosulphate (VI) acid and then K₂Cr₂O₇ solutions, a blue-black colour was produced. In this reaction, the

1. A.iodide ion is oxidized
2. B.tetraoxosulphate (VI) acid acts as an oxidizing agent
3. C.starch has been oxidized
4. D.K₂Cr₂O₇ is oxidized.

The diagram shows the reaction path of an exothermic reaction. The heat of reaction is represented by

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

Which of the following statements is TRUE?

1. A.The dissolution of NaOH_(s) in water is endothermic
2. B.The heat of solution of NaOH_(s) is positive
3. C.The NaOH_(s) gains heat from the surroundings
4. D.The heat of solution of NaOH_(s) is negative.

Which of the following will produce the greatest increase in the rate of the chemical reaction represented by the equation Na₂S₂O_3(aq) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l) + SO_2(g) + S_(s)?

1. A.A decrease in temperature and an increase in the concentration of the reactants
2. B.An increase in the temperature and a decrease in the concentration of the reactants
3. C.An increase in the temperature and an increase in the concentration of the reactants.
4. D.A decrease in the temperature and a decrease in the concentration of the reactants.

Which property of a reversible reaction is affected by a catalyst?

1. A.Heat content (enthalpy).
2. B.Energy of activation
3. C.Free energy change
4. D.Equilibrium position

Which of the following is used in fire extinguishers?

1. A.Carbon (II) oxide
2. B.Carbon (IV) oxide
3. C.Sulphur (IV) oxide
4. D.Ammonia.

When H₂S gas is passed into a solution of iron (III) chloride, the colour changes from yellow to green. This is because

1. A.H₂S is reduced to S
2. B.Fe³⁺ ions are oxidized by H₂S
3. C.Fe³⁺ ions are oxidized by Fe²⁺ ions
4. D.Fe³⁺ ions are reduced to Fe²⁺ ions.

Carbon (II) oxide may be collected as shown in the figure because it

1. A.is heavier than air
2. B.is less dense than air
3. C.is insoluble in water
4. D.burns in oxygen to form carbon (IV) oxide.

In the reaction C₆H₁₀O_5(s) → 6C_(s) + 5H₂O (conc. H₂SO₄), concentrated H₂SO₄ is acting as

1. A.a reducing agent
2. B.an oxidizing agent
3. C.a dehydrating agent
4. D.a catalyst.

Suitable reagents for the laboratory preparation of nitrogen are

1. A.sodium dioxonitrate (III) and ammonium chloride
2. B.sodium trioxonitrate (V) and ammonium chloride
3. C.sodium chloride and ammonium trioxonitrate (V)
4. D.sodium chloride and ammonium dioxonitrate (III).

The thermal decomposition of copper (II) trioxonitrate (V) yields copper (II) oxide, oxygen and

1. A.nitrogen (II) oxide
2. B.nitrogen (I) oxide
3. C.nitrogen (IV) oxide
4. D.nitrogen

Chlorine is produced commercially by

1. A.electrolysis of dilute hydrochloric acid
2. B.electrolysis of brine
3. C.neutralization of hydrogen chloride
4. D.heating potassium trioxochlorate (V).

Which of the following is used in the manufacture of glass?

1. A.Sodium chloride
2. B.Sodium trioxocarbonate (IV).
3. C.Sodium tetraoxosulphate (VI).
4. D.Sodium trioxonitrate (V).

Aluminium is extracted commercially from its ore by

1. A.heating aluminium oxide with coke in a furnace
2. B.the electrolysis of fused aluminium oxide in cryolite
3. C.treating cryolite with sodium hydroxide solution under pressure
4. D.heating sodium aluminium silicate to a high temperature.

Crude copper can be purified by the electrolysis of CuSO_4(aq) if

1. A.platinum electrodes are used
2. B.the crude copper is made the anode of the cell
3. C.the crude copper is made the cathode of the cell
4. D.crude copper electrodes are used.

The IUPAC name for CH₃CH₂CH(CH₃)COOH is

1. A.2 –methylbutanoic acid
2. B.2 –methyl-1-hydroxyketone
3. C.2–methyl-1-hydroxy aldehyde
4. D.2-methylpentanoic acid.

Methylethanoate reacts with ammonia to yield

1. A.methylamine and ethanol
2. B.ethylamine and methanol
3. C.methanamide and ethanol
4. D.ethanamide and methanol

Alkanoates are formed by the reaction of alkanoic acids with

1. A.Alkyl halides
2. B.alkanols
3. C.ethers
4. D.sodium

The acidic hydrogen in the compound H–C≡C–CH=CH–CH₃ (carbons numbered 1 to 5 from the left) is the hydrogen attached to carbon number

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

The four classes of hydrocarbons are

1. A.ethane, ethene, ethyne and benzene
2. B.alkanes, alkenes, alkynes and aromatics
3. C.alkanes, alkenes, alkynes and benzene
4. D.methane, ethane, propane and butane.

Alkanes → smaller alkanes + alkenes + hydrogen (400 – 700 °C, catalyst). The above reaction is known as

1. A.photolysis
2. B.cracking
3. C.isomerization
4. D.reforming

In the reaction 2(C₆H₁₀O₅)_n + nH₂O → nC₁₂H₂₂O₁₁ (diastase, 60 °C), diastase is functioning as

1. A.a dehydrating agent
2. B.a reducing agent
3. C.an oxidizing agent
4. D.a catalyst

Which of the following compounds has the highest boiling point?

1. A.CH₃CH₂CH₂CH₂OH
2. B.CH₃CH₂CH₂CHO
3. C.CH₃CH₂CH₂CH₃
4. D.CH₃CH₂OCH₂CH₃.

Detergents have the general formula

1. A.R(CH₂)_nOH
2. B.RSO₃⁻Na⁺
3. C.RCO₂⁻Na⁺
4. D.RCO₂H.

What process would coal undergo to give coal gas, coal tar, ammoniacal liquor and coke?

1. A.Steam distillation
2. B.Destructive distillation
3. C.Liquefaction
4. D.Hydrolysis.