Electrolysis - Chemistry Jamb Past Questions and Answers

Question 6 :

• JAMB 1979

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 aluminium purer
D. It prevents aluminium from getting oxidized
E. It protects the carbon electrodes used in the process

Question 7 :

• JAMB 1980

The chemical reaction which takes place at the anode (positive electrode) in electrolysis is?

A. Oxidation
B. Hydrolysis
C. Dissociation
D. Reduction
E. Disproportionation

Question 8 :

• JAMB 1980

Which of the following does NOT happen when a zinc rod is introduced into a solution of copper (ll) sulphate?

A. Electrons flow towards the zinc rod
B. The zinc rod dissolves
C. The temperature of the soil changes
D. The blue colour of the solution gradually disappears
E. Copper metal is deposited

Question 9 :

• JAMB 1980

A cold aqueous solution of sodium chloride is electrolyzed using a graphite anode and an iron cathode. In the course of the electrolysis the electrolyte is continuously stirred. The liquid left after electrolysis will therefore consist of?

A. Sodium hydroxide solution
B. Chlorine water
C. Pure water
D. Sodium hypochlorite solution
E. Hydrochloric acid solution

Question 10 :

• JAMB 1980

When chlorine gas is passed into a solution of sulphur dioxide?

A. Sulphur dioxide is reduced to sulphur
B. The chlorine is oxidized to hydrochloric acid
C. Dilute sulphuric acid and hydrochloric acid are produced
D. Hydrochloric acid and sulphur are produced
E. Sulphur trioxide is the only product