Question 586:

• JAMB 1989

Calcium hydroxide is added in the treatment of town water supply to

A. Kill bacteria in the water
B. Facilitate coagulation of organic particles
C. Facilitate sedimentation
D. Improve the taste of the water

Question 587:

• JAMB 1989

A hydrated salt of formula MSO₄.xH₂ O CONTAINS 45.3% by mass of water of crystalisation. Calculate the value of x [M = 56, S = 32, O = 16, H = 1 ]

A. 3
B. 5
C. 7
D. 10

Question 588:

• JAMB 1989

Using 50 cm ³ of 1 M potassium hydroxide and 100cm ³ of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm ³ of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [ = 39, S = 32, O = 16, H = 1]

A. 50, 50
B. 25, 50
C. 50, 25
D. 25, 25

Question 589:

• JAMB 1989

A solution of calcium bromide contains 20 g dm ³ What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80]

A. 0. 1, 0 . 1
B. 0. 1, 0. 2
C. 0. 1, 0. 05
D. 0.05, 0.1

Question 590:

• JAMB 1989

The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as

A. An allotropic oxide
B. An amphoteric oxide
C. A peroxide
D. A dioxide