Waec Chemistry 1997 Past Questions and Answers

Question 56:

• WAEC 1997

(a) State Gay Lussac's law of combining volumes
(b) Hydrogen reacts with oxygen according to the following equation;
2H\(_{2(g)}\) + O\(_{2(g)}\) ---> 2H\(_2\)O\(_{(g)}\). If 50cm\(^3\) of hydrogen were sparked with 30cm\(^{3}\) of oxygen, calculate the volume of unused oxygen after cooling to the initial temperature and pressure.

Question 57:

• WAEC 1997

(a) Mention three chemical properties of chlorine
(b) What type of reaction is represented by each of the following equations?
(i) Mg\(_{(s)}\) + 2HCI\(_{(aq)}\) --> Mg\(_2\)Cl\(_{2(aq)}\) + H\(_{2(g)}\)
(ii) Ag\(^+_{aq}\) + Cl\(^-\)\(_{(aq)}\) ----> AgCl\(_{(s)}\)

Question 58:

• WAEC 1997

(a) Give one example of a metal which:
(i) can displace hydrogen from cold water
(ii) at red-heat, reacts reversibly with steam
(iii) does not react with dilute hydrochloric acid

(b) When dry hydrogen was passed over lead (II) oxide, a greyish solid J was obtained.
(i) Identify J
(ii) What type of reaction was involved in the formation of J from lead (II) oxide?

Question 59:

• WAEC 1997

(a)(i) Define entropy
(ii) What term is used to describe a reaction in which heat is absorbed from the surrounding?
(b) State two conditions that can lead to ineffective collisions during a chemical reaction.

Question 60:

• WAEC 1997

(a)(i) List two reactants for the laboratory preparation of ammonia
(ii) State three physical properties of ammonia
(iii) Describe in outline, the manufacture of ammonia by the Haber process.

(b) Write an equation in each case to show the:
(i) reaction between ammonia gas and heated copper (II) oxide
(ii) action of heat on ammonium trioxocarbonate (IV)

(c)(i) Which industrial process is used for convey ammonia to trioxonitrate (V) acid?
(ii) Give the reason why electropositive metals do not generally are off hydrogen with dilute trioxonitrate (V) acid
(d) Give one example in each case, to show how trioxonitrate (V) acid reacts generally with: (i) bases (ii) non-metals.