Waec Chemistry 1996 Past Questions and Answers

Question 46:

• WAEC 1996

(a) State the monomer units of (i) polyethene; (ii) cellulose
(b) Name the two fuels obtained when steam and air are passed over red-hot coke.

Question 47:

• WAEC 1996

(a) Determine the oxidation number of manganese in MnO\(_4\)
(b)(i) List two metals that are extracted from their ores by electrolysis
(ii) Give one difference between a conductor and an electrolyte.

Question 48:

• WAEC 1996

(a)(i) Explain what is meant by an effective collision
(ii) What does each term represent in the following expression? \(\Delta G\) = \(\Delta H\) — T\(\Delta\)S
(iii) What deduction can be made about a system given that the value of its \(\Delta\)G is zero?

(b)(i) State Le Chatelier's principle.
(ii) Suggest three conditions necessary for maximum yield of A\(_2\)B in the reaction represented by the following equation 2A\(_{2(g)}\) + B\(_{2(g)}\) \(\rightleftharpoons\) 2A\(_2\)B\(_{(g)}\) \(\Delta\)H = xkj.
(iii) Write an expression for the equilibrium constant of the reaction in (b)(ii) above.

(c)(i) Give the reason why a log of wood of a given mass does not burn out as quickly as sawdust of the same mass, under the same conditions.
(iii) List two examples of chemical reactions that are catalyzed by light

Question 49:

• WAEC 1996

(a)(i) Give one major use of alkenes.
(ii) Name the simplest alkane that exhibits structural isomerism
(iii) Determine the molar mass of an alkane that is represented as C\(_x\)F\(_{22}\). [H = 1, C = 12]
(iv) List two types of chemical reactions which the alkenes and alkynes undergo.

(b)(i) State the type of reaction involved in the conversion of palm oil to margarine.
(ii) Give the reason why the palm oil for manufacturing margarine is first treated activated charcoal
(iii) What is commonly used to catalyse the conversion of vegetable oils to margarine?

(c)(i) Name the class of organic compounds to which oils belong.
(ii) Describe briefly procedure for the manufacture of soap from vegetable oils
(iii) Explain why the presence of calcium ions in domestic water supply wastes soap.

Question 50:

• WAEC 1996

(a)(i) What is an acid?
(ii) List three chemical properties of tetraoxosulphate (VI) acid
(iii) Give two uses of tetraoxosulphate (VI) acid.

(b)(i) Describe a suitable laboratory procedure for preparing a sample of zinc tetraoxosulphate (VI) crystals, starting from zinc oxide.
(ii) Write two equations to show why zinc oxide is classified as an amphoteric oxide.

(c) Zinc reacts with copper (II) tetraoxosulphate (VI) according to the following equation: Zn + CuSO\(_4\) -> ZnSO\(_4\) + Cu
(i) State the type of reaction involved
(ii) Determine the mass of zinc that would react completely with 8.0g of copper (II) tetraoxosulphate (VI). [CuSO\(_4\) = 160; Zn = 65]