Hard and soft water - Jamb Chemistry Past Questions and Answers

Question 1:

• JAMB 2019

A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by

A. Boiling the water
B. Adding excess calcium hydroxide
C. Adding a calculated amount of calcium hydroxide
D. Adding sodium carbonate
E. Adding magnesium hydroxide

Question 2:

• JAMB 2019

The method that can be used to convert hard water to soft water is

A. Chlorination
B. Passage over activated charcoal
C. The use of an ion-exchange resin
D. Aeration

Question 3:

• JAMB 1978

A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by

A. Boiling the water
B. Adding excess calcium hydroxide
C. Adding a calculated amount of calcium hydroxide
D. Adding sodium carbonate
E. Adding magnesium hydroxide

Question 4:

• JAMB 1984

Water is said to be 'hard' if it

A. Easily forms ice
B. Has to be warmed before sodium chloride dissolves in it
C. Froms an insoluble scum with soap
D. Contains nitrates
E. Contains sodium ions

Question 5:

• JAMB 1997

A major process involved in the softening of hard water is the?

A. Conversation of a soluble calcium salt to its trioxoncarbonate (lV)
B. Decomposition of calcium rioxocarbonate (lV)
C. Conversion of an insoluble calcium salts to its trioxocarbonate (lV)
D. Oxidation of calcium atoms to its ions