JAMB Chemistry Past Questions & Answers - Page 439

2,191.

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

Correct answer is D

No explanation has been provided for this answer.

2,192.

Which of the following metals cannot replace hydrogen from water or steam?

A.

Sodium

B.

Magnesium

C.

Iron

D.

Calcium

E.

Copper

Correct answer is E

No explanation has been provided for this answer.

2,193.

When each of the nitrates of Potassium, Magnesium and iron is heated,

A.

all the nitrates decompose to their oxides

B.

the nitrate of magnesium gives the nitrite and oxygen

C.

the nitrates of magnesium and iron give the oxides

D.

the nitrate of iron gives the nitrite and oxygen

E.

the nitrate of the magnesium is not decomposed

Correct answer is C

No explanation has been provided for this answer.

2,194.

The pH of four solutions W, X, Y, Z are 4, 6, 8, 10 respectively, therefore

A.

none of these solutions is acidic

B.

the pH of Y is made more acidic by addition of distilled water

C.

Z is the most acidic solution

D.

W is the most acidic solution

E.

X is neutral

Correct answer is D

W is the most acidic solution since 4 < 6 < 8 < 10. The lower the value on the pH scale, the more acidic a solution.

2,195.

When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as

A.

disintegration

B.

polymerization

C.

cracking

D.

degradation

E.

distillation

Correct answer is C

No explanation has been provided for this answer.