1979 JAMB CHEMISTRY QUESTIONS

UME 1979 CHEMISTRY QUESTIONS

1.     Organic compound X has the following properties; (i) It is not miscible with water (ii) It has boiling point of 77⁰C (iii) It has a sweet odour. (iv) It is insoluble in sodium hydrogen carbonate solution. (v) It does not decolourize bromine water. X is therefore A. Methane, B. ethanoic acid, C. ethane, D. ethylethanoate, E. Carbon tetrachloride

2.     Which one are the correct IUPAC names for H-CO₂CH₃ and CH = CH. A. Methyl methanoate and ethane, B. Methanoic acid and ethyne, C. ethyl methanoate and ethyne, D. Methyl methanoate and ethyne, E. ethanoic acid and ethane

3.     Which of the following substances are all made by the process of polymerization? A. Nylon and soap, B. Ethanoic acid, margarine and ethanol, C. Nylon and artificial rubber, D. Soap and butane, E. margarine and nylon

4.     The reaction of zinc with copper (II) ions in aqueous solution can be represented as follows: Cu²⁺_(aq) + Zn_(s)  + Zn²⁺_(aq). Which of the following is the most complete description of this reaction? A. copper (II) ions are being reduced, B. Zinc is being oxidized, C. copper(II)ions are being reduced, D. copper(II)ions and zinc are being oxidized, E. copper(II)ions are being reduced and zinc oxidized.

5.     The oxidation state of manganese in potassium permanganate is A. +7, B. +5, C. +3, D. +2, E. +1

6.     When carbondioxide is bubbled into limewater, a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is A. calcium carbonate is formed which gradually dissolves, B. Calcium hydrogen carbonate is precipitated and then dissolves, C. Calcium carbonate is formed which on reaction with further carbon dioxide forms soluble calcium hydrogen carbonate, D. concentration of the solution has occurred with the deposition of calcium hydroxide, E. the solution has become saturated and solid carbon-dioxide has been deposited

7.     The following reactions are stages in important industrial processes: (i) N_2(g) + 3H_2(g) 2NH_3(g) ∆H is negative (i) 2SO_2(g) + O_2(g) 2SO_3(g) ∆H is negative (iii) N_2(g) + O_2(g) 2NO(g) ∆H is positive. Which of the above forward reactions is favoured by (i) a decrease in the concentration of the product, and (ii) an increase in temperature? A. I, B. II, C. III, D. I & II, E. I & III       

8.    

CH3 – C – CH = CH2

CH3

H

The IUPAC name for the compound below is:

A. 2-methylbut-3-ene, B. 2-methylbut-4-ene, C, 3-methylbut-2-ene, D. 3-methylbut-2-ene, D. 3-methylbut-1-ene, E. 3-methylpent-1-ene

9.     Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of sand, water and methanoic acid? A. fractional distillation, B. filtration followed by distillation, C. neutralization with sodium hydroxide followed by distillation, D. neutralization with sodium hydroxide followed by filtration, E. esterification with ethanol followed by distillation

10.  Which of the following statements applies during the electrolysis of sodium hydroxide solution using platinum electrode? A. Na⁺ ions are discharge at the cathode, B. Hydrogen ions are discharge at the cathode, C. the concentration of sodium hydroxide decreases at both electrode compartments, D. the concentration of sodium hydroxide increases at the cathode only, E. the concentration of sodium hydroxide increases at the anode only

11.  Which of the following statements is true? When the potassium atom forms its ion A. it gains one electron and becomes neutral, B. its atomic number decreases, C. it achieves electronic configuration of argon, D. it loses one proton, E. it loses one neutron

12.  Which of the following contains two amphoteric oxides?  A. sodium oxide, zinc oxide, magnesium oxide, B. Aluminum oxide, calcium oxide, zinc oxide, C. potassium oxide, lithium oxide, carbon dioxide, D. silver oxide, lead oxide, sodium oxide, E. sulphur dioxide, Aluminum oxide, carbon monoxide.

13.  Helium atoms are chemically unreactive because A. there are no electrons around the nucleus, B. the number of protons equals the number of electrons, C. there are equal numbers of protons and neuron in the nucleus, D. the outer electron shell is completely filled, E. the atoms contains only protons.

14.  50cm³ of hydrogen are sparked with 20cm³ of oxygen at 100^oC and 1 atmosphere. The total volume of the residual gases is A. 50cm³, B. 10cm³, C. 40cm³, D. 30cm³, E. 70cm³

15.  How many grams of HBr would exactly be required to react with 2g of propyne? (C = 12, H = 1, Br = 80) A. 4.1g, B. 6.1g, C. 8.1g D. 10.1g, E. 16.2g

16.  When ammonium, potassium and calcium carbonates are each separately heated A. none of them will decompose, B. each of them will decompose to give carbondioxide and the respective oxide, C. ammonium carbonate and potassium carbonate will not decompose, D. only ammonium carbonate and calcium carbonate will decompose to carbon dioxide and the respective oxide, E. ammonium carbonate will decompose to give carbon dioxide, water and ammonia

17.  The structural formula of ethanoic acid is

18.  If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bring sunlight for a while: A. the solution will give out chlorine gas and hydrogen chloride gas, B. the solution will produce chlorine gas and oxygen, C. the solution will give out oxygen thereby producing hypochlorous acid, D. the solution will give out oxygen gas leaving behind aqueous, E. the solution is decomposed, giving out oxygen, hydrogen and chlorine.

19.  12g of solid potassium chlorate (KCIO₃) were added to 40g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate started forming at 66^oC. The solubility of potassium chlorate at 66^oC is therefore A. 66, B. 33, C. 10, D. 20, E. 30

20.  In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:

	Anode	Cathode
A	Sulphur	hydrogen
B	Hydrogen	Oxygen
C	Oxygen	Hydrogen
D	Hydrogen	Sulphate ions
E	Sulphur	Oxygen

21.  The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is A. N₂O₂, B. NO, C. NO₂, D. N₂O, E. N₂O₃

22.  When a piece of charcoal enclosed in a cylinder containing air is ignited A. the total volume of air is increased, B. the relative amount of oxygen present is increased, C. the relative amount of nitrogen present is decreased, D. the relative amount of carbondioxide present is increased, E. the ratio of oxygen to nitrogen in the system is increased.

23.  Indicate which of the following statements is not true as we move from left to right along the periodic table: A. Atomic number of elements increases, B. atomic mass of elements increases, C. electropositive character of elements increases, D. electronegative character of elements increases, E. number of electron in the outermost orbits of elements increases.

24.  0.1 Faraday of electricity was passed through a solution of copper (II) sulphate. The maximum weight of copper deposited on the cathode would be A. 64.0g, B. 32.0g, C. 16.0g, D.6.4g, E. 3.2 [Cu= 64]

25.  Which of these compounds will NOT give an oxygen gas on heating? A. manganese dioxide, B. Hydrogen peroxide, C. zinc nitrate, D. sodium nitrate, E. ammonium nitrate

26.  In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because A. it makes bauxite a better conductor of electricity, B. it makes bauxite melt at a lower temperature, C. it makes aluminum purer, D. it prevents aluminum from getting oxidized, E. it protects the carbon electrodes used in the process.

27.  In the redox reaction

2Fe²⁺ + Cl₂  2Fe³⁺ + 2Cl A. Cl₂ is reduced because it has lost electrons, B. Cl₂ is reduced because its oxidation number has decreased, C. Cl₂ is reduced because its molecule is changed to two ions, D. Fe²⁺ is reduced because it has lost electrons, E. Fe²⁺ is reduced because it has gained electrons.

28.  An anhydride is A. a compound which has no water of crystallization, B. an oxide whose solution in water has a pH less than 7, C. an oxide whose solution in water has a pH less than 7, D. an oxide that has hydrogen atoms, E. an amphoteric oxide.

29.  In which of the following reactions is sulphurdioxide acting as an oxidizing agent? A. SO₂ + 2HNO₃ H₂SO₄ + NO₂ + Heat, B. 2SO₂ + 2H₂O + O₂ H₂SO_4, C. SO₂ + 2H₂O + Cl₂ H₂SO₄ + 2HCl, D. SO₂ + 2H₂S + 2H₂O _,  E. SO₂ + H₂O H₂SO₃

30.  Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by A. dissolving it in water, recrystallizing it, and then drying in the oven, B. passing it through a concentrated aqueous solution of sodium hydroxide, C. passing it through concentrated sulphuric acid, D. passing it through calcium oxide, E. passing it through anhydrous calcium chloride.

31.  Starch can be converted to ethyl alcohol by A. distillation, B. fermentation, C. isomerization, D. cracking, E. cooking

32.  The reaction between hydrogen and iodine may be represented by the equation H_2(g) + I_2(g) 2HI_(g)  and is exothermic. Therefore, A. an increase in temperature favours the forward reaction, B. an increase in pressure favours the backward reaction, C. both pressure and temperature must be increased to favour the forward reaction, D. a decrease in temperature will favour the forward reaction, E. a decrease in pressure and an increase in temperature will favour the forward reaction.

33.  Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weights, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? A. Z is efflorescent, B. Y and Z are efflorescent, C. Y and Z are deliquescent, D. Y and Z are hygroscopic, E. Y is deliquescent.

34.  In the manufacture of iron in the blast furnace, iron(III)oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions? A. the coke is a powerful reducing agent and easily converts the ion oxide to ion, B. the calcium carbonate reacts with SiO₂, an earthly impurity in the ore, to form calcium silicate, C. the coke will react with the iron produced to form steel, D. all the carbon dioxide required in the process comes from the decomposition of the calcium carbonate, E. the calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity.

35.  Which of the following statement is true? A. an increase in the temperature of a given mass of gas increases the number of gas molecules, B. an increase in the temperature of the gas does not affect the kinetic energy, C. an increase in the pressure of the gas is proportional to the increase in volume, D. a decrease in the pressure of the gas is proportional to the increase volume at constant temperature, E. a decrease in the pressure of the gas decreases the number of gas molecules present.

36.  The vapour density of a gas may be defined as A. the mass of a unit volume of the gas compared to an equal volume of water vapour, B. the mass of a unit volume of the gas compare to an equal volume of hydrogen, C. the mass of a unit volume of the gas compared to an equal volume of oxygen, D. the mass of a unit volume of the gas minus the vapour pressure of water, E. two times the relative molecular mass of the gas.

37.  The reaction: 3C_(s) + 2Fe₂O_3(s) 4Fe_(s) + 3CO_2(g); ∆H = - 46.0KJ is A. Adiabatic, B. Isobaric, C. endothermic, D. exothermic, E. isothermic

38.  The solution of a sample in a tube will be identified as a chloride if it gives A. a white precipitate on addition of AgNO₃ and barium chloride solutions, B. a white precipitate when acidified with dilute HNO₃ and then AgNO₃ solution added, C. a white precipitate when acidified with dilute HNO₃ and then AgNO3 solution added, D. a white precipitate when acidified with dilute H₂SO₄ and then barium nitrates solution added, E. a pungent smell of chlorine gas when dilute HCI and MnO₂ are added.

39.  Hydrogenation may be effected by A. the removal of hydrogen from an alkane in the presence of a catalyst, B. the addition of hydrogen to an alkan in the presence of a catalyst, C. the addition of hydrogen to an alkyne, D. the removal of hydrogen from an alkyne, E. the addition of hydrogen to an ethyl alcohol

40.  Two metallic ions associated with hard water are A. copper and zinc, B. magnesium and silver, C. calcium and magnesium, D. potassium and tin, E. Sodium and lead

41.  Bronze is an alloy of A. copper, zinc and nickel, B. aluminum and copper, C. copper and zinc, D. tin and zinc, E. tin and copper

42.  Phosphorus burns in oxygen according to the equation: P4 + 5O₂  P₄O₁₀ how many litres of oxygen will be required at S.T.P. for complete oxidation of 12.4g of phosphorus? A. 5.20, B. 11.20 C. 2.24, D. 20.20, E. 6.20. (P = 31, O = 6 and molar volume of a gas at S.T.P = 22.4 litres)

43.  On oxidizing anhydrous iron (II) sulphate, in addition to producing iron(III) oxide, which of the following are produced? A. SO_2(g) + FeS_(s), B. SO_3(g) + FeS_(s), C. SO_2(g) + FeS_3(s), D. SO_2(g) + H₂S_(g), E. SO_3(g) + H₂S_(g)

44.  One of the following techniques can be used to show that chlorophyll pigment is a mixture of chemical compounds and not a single-coloured compound. A. crystallization B. hydrolysis C. sublimation D. filtration E. chromatography.

45.  A gas occupies 30.0dm³ at S.T.P. what volume would it occupy at 91^oC and 380mm Hg? A. 20.0dm³, B. 40.0dm³ C. 60.0dm³ D. 80.0dm³, E. 100.0dm³

46.  When excess ethanol is heated to 145oC in the presence of concentrated sulphuric acid, the product is A. diethyl ether B. ethyne C. diethyl sulphate, D. acetone, E. ethanoic acid.

47.  Which of the following raw materials would be required for the smelting of iron ore in a blast furnace? A. CaO₃ B. Zn(NO₃)₂, C. CuSO₄ D. AICI₃ E. CaSO₄

48.  A piece of metal (M) is dissolved in nitric acid and the resulting solution is treated with a small quantity of sodium hydroxide to produce a white precipitate (B) which redissolves on the addition of excess alkali. The precipitate (B) when ignited in a crucible produces the oxide of the metal (M). the metal M is A. Zn B. Cu, C. AI, D. Au, E. Ca

49.  Pick out the correct statement. A. Zinc heated to redness reacts with steam to give oxygen and zinc oxide, B. Zinc heated to redness reacts with steam to give oxygen and hydrogen, C. Zinc does not react with hot or cold water, D. Zinc reacts with hot water to from zinc oxide and hydrogen, E. zinc reacts very easily with cold water to give zinc oxide and hydrogen.

50.  Consider the following exothermic reaction: 2SO_2(g) + O_2(g) = 2SO_3(g) if the temperature of the reaction is reduced from 800^oC to 500^oC, and no other change takes place, then, A. the reaction rate increases, B. concentration of SO₃ decreases C. concentration of SO₃ increases, D. SO₂ gas becomes unreactive, E. O₂ gas becomes unreactive