WAEC Chemistry 1988 Past Questions

(a) Name two allotropes of carbon

(b) Name two products of the destructive distillation of coal and state one use of each.

 (a) Give one example of;

(i) heavy chemicals

(ii) fine chemicals

(b) Write the structural formulae and the names of compounds having the formula CH\(_4\)CI,

(a) Arrange the following in their correct order of increasing energy: alpha particles, gamma rays and beta particles

(b) State one difference between nuclear fission and nuclear fusion

50cm\(^{3}\) of sulphur (IV) oxide were produced at s.t.p. when some quantity of powdered sulphur were burnt in excess oxygen

(a) Write the equation for the reaction

(b) Calculate the volume of oxygen used up during the reaction

(c) Which of the gas laws is applicable? State the law.

(a) How does the collision theory explain the rate of a chemical reaction?
(b) State how each of the following affects the rates of chemical reactions:

(i) surface area (ii) catalyst

(a) Write the ionic equation for the reaction between zinc powder and silver trioxonitrate (VI) solution

(b) Which substance in (a) above is (i) oxidized, (ii) reduced?

(c) State two applications of oxidation numbers

 (a) What is a carbohydrate?

(b) Name two types of carbohydrates and give one example of each type

(a) Name the major raw materials used in the manufacture of the following:

(i) polythene

(ii) margarine

(iii) cement

(b) State one problem associated with oil producing areas

Distinguish between cracking and reforming. Of what importance are the two processes in the petroleum industry?

State Gay-Lussac's law and illustrate the law with one chemical reaction.

(a) Explain with equation where appropriate, the functions of the following substances in the Solvay Process:

(i) limestone,

(ii) ammonia,

(iii) brine.

(b) Explain why the reaction between aqueous sodium trioxocarbonate (IV) solution and dilute hydrochloric acid is a neutralization reaction.

(c) Calculate the mass of sodium trioxocarbonate (IV) produced by the complete decomposition of 16.8g of sodium hydrogen trioxocarbonate (IV) (H = 1, O = 16, Na = 23, S = 33)

(a) Explain why transition metals

(i) have high melting points

(ii) have variable oxidation states,

(iii) exhibit paramagnetism

(b) (i) Name the impurities present in bauxite

(ii) State how the impurities in bauxite are removed

(ii) Explain why aluminium oxide is said to be amphoteric.

(c) (i) Describe the electrolysis of copper (II) tetraoxosulphate (VI) solution, using copper electrodes.

(ii) Will the colour of the copper (II) tetraoxosulphate (VI) solution change at the end of the electrolysis described in (c)(i) above? Give reasons for your answer.

(a) Write the structural formula of:

(i) 2, 2, 4 - trimethylpentane, (ii) ethylmethanoate, (iii) trans 2, 3 - dimethylbut - 2-ene.

(b) Write the structure of the straight-chain compound that is isomeric with 2,2,4 - trimethylpentane.

(c) Write chemical equations to illustrate the oxidation of: (i) a secondary alkanol (ii) a dihydric alkanol.

(d) When-Crushed cassava was warmed with dilute hydrochloric acid, a sweet-tasting compound, D was obtained. When compcund D was treated with the enzyme, zymase and the mixture distilled a clear and colourleCsliduid, E was obtained. When liquid E was warmed with eth anoic acid i n the presence of a few drops of concentrated tetraoxosulphate (V1) acid, a compound F, with fruity smell was obtained

. (i)To what class of compounds does D belong?

(ii) Name E and F

(iii) Write the fun-ctional group in F

(iv) Write the equation for the reaction between E and ethanoic acid in the presence of concentrated tetraoxosulphate (VI) acid.

(v) Name the type of reaction that takes place between E and ethanoic acid.

(e) Arrange the followingcompounds in their correct order of increasing boiling points: CH\(_3\)CH\(_2\)CH\(_2\)OH, CH\(_3\)CH\(_2\)CH\(_2\)CH\(_2\)CH\(_2\)CH\(_3\) and CH\(_2\)CH\(_2\)CH\(_2\)CH\(_3\); Explain the order.

(a) An element X is represented as \(^{40}_{20} X\)

(i) How many electrons and how many neutrons are present in the atom of X?

(ii) Write the electronic configuration of the atom

(b) Chlorine, whose atomic number is 17, reacts with the element X to form a compound.

(i) What type of bond is formed between X and chlorine?

(ii) Explain how the bond between X and chlorine is formed

(iii) Write the formula of the compound formed and statelhree properties of the compound.

(c) Chlorine has two isotopes of mass numbers 35 and 37 respectively. Suggest the possible relative molar masses of a chlorine molecule.

(d) Calculate the mass of one atom of carbon, given that one mole of carbon weighs 12.0g. (L = 6.02 x 10\(^{23}\))