Question 516:

• JAMB 1987

A stream of air was successively passed through three tubes X, Y and Z containing a concentrated aqueous solution of KOH, red hot copper powder and fused calcium chloride respectively. What was the composition of the gas emanating from tube Z?

A. CO₂ ad ithe inert gases
B. N₂, CO₂ and the inert gases
C. N₂ and the inert gases
D. Water vapour, N₂ and the inert gases

Question 517:

• JAMB 1987

In the purification of town water supply, alum is used principally to?

A. Kill bacteria
B. Control the pH of water
C. Improve the taste of the water
D. Coagulate small pasrticles of mud

Question 518:

• JAMB 1987

Which of the following water samples will have the highest titre value when titrated for the Ca²⁺ ions using soap solution?

A. Permanently hard water after boiling
B. Emporarily hard water after boiling
C. Rain water stored in a glass jar for two years
D. Permanent hard water passed through permuitit

Question 519:

• JAMB 1987

Oil spillage in ponds and creeks can be cleaned up by?

A. Burning off the oil layer
B. Spraying with detergent
C. Dispersal with compressed air
D. Spraying with hot water

Question 520:

• JAMB 1987

The solubility of Na₃AsO₄(H₂O)₁₂ is 38.9g per 100g H₂O. What is the mass percentage of Na₃AsO₄ in the saturated solution?
(As = 75, Na = 23, O = 16, H = 1)

A. 87.27%
B. 38.9%
C. 19.1%
D. 13.7%