JAMB Chemistry Past Questions & Answers - Page 23

111.

Addition of charcoal to the filter bed of sand during water treatment for township supply is to?

A.

prevent goiter

B.

prevent tooth decay

C.

remove odour

D.

kill germs

Correct answer is C

Activated Carbon filters are excellent at removing chlorine and related poor taste and odor.

112.

On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell

A.

cu\(^{2+}\)

B.

sn\(^{2+}\)

C.

fe\(^{2+}\)

D.

zn\(^{2+}\)

Correct answer is A

The arrangement of elements in order of increasing electrode potential values is called electrochemical series.

K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Ag > Au.

113.

A chemical widely used as a fertilizer is?

A.

galena

B.

bauxite

C.

emerald

D.

nitrochalk

Correct answer is D

Calcium ammonium nitrate or CAN, also known as nitro-limestone or nitrochalk, is a widely used inorganic fertilizer.

114.

Addition of sodium chloride to water to form a solution would  lead to?

A.

increase in freezing point and increase the boiling point

B.

increase in freezing point and decrease the boiling point

C.

decrease in freezing point and decrease the boiling point

D.

decrease in freezing point and increase the boiling point

Correct answer is D

If you add salt to water, you lower its freezing point as well as raise its boiling point.

115.

An organic compound which liberate carbon(iv)oxide from trioxocarbonate(iv) solution is likely to be?

A.

C\(_2\)H\(_5\)OH

B.

C\(_3\)H\(_4\)

C.

C\(_6\)H\(_6\)

D.

CH\(_3\)COOH

Correct answer is D

Carboxylic acids and enols react with sodium bicarbonate to liberate carbon dioxide.

E,g CH\(_3\)COOH