Chemistry 1990 Waec Past Questions and Answers

Question 31 :

• WAEC 1990

Which of the following compounds crystallizes without water of crystallization?

A. Na₂CO₃
B. CuSO₄
C. MgSO₄
D. NaCI
E. FeSO₄

Question 32 :

• WAEC 1990

The following metals are extracted by the electrolytic method except

A. Potassium
B. Calcium
C. Sodium
D. Tin
E. Magnesium

Question 33 :

• WAEC 1990

Petrol can be obtained from diesel by

A. Distillation
B. Cracking
C. Catalysis
D. Polymerization
E. Dehydrogenation

Question 34 :

• WAEC 1990

(a) Write the electronic configuration of an element with atomic number 15, indicating the distribution of electrons in the energy sub-levels
(b) Give the formula and the colour of the complex formed between ammonia and copper (II) ions

Question 35 :

• WAEC 1990

(a) Give two reasons why carbon(IV) oxide is used for extinguishing fire
(b) Explain briefly the water softening action of cation exchane resins.