JAMB Chemistry Past Questions & Answers - Page 193

962.

A piece of filter paper moistened with lead (ll) ethanoate solution turns black when the paper is dropped into a gas likely to be

A.

sulphur (VI) oxide

B.

hydrogen chloride

C.

sulphur (VI) oxide

D.

hydrogen sulphide

Correct answer is D

No explanation has been provided for this answer.

963.

The highest rate of production of carbon (lV) oxide can be achieved using

A.

0.05 mol -3HCI and 5g powdered CaCO3

B.

0.05 mol -3HCI and 5g lump CaCO3

C.

0.10 mol -3HCI and 5g powdered CaCO3

D.

0.025 mol -3HCI and 5g powdered CaCO3

Correct answer is C

No explanation has been provided for this answer.

964.

An increase in entropy can best be illustrated by

A.

mixing of gases

B.

freezing of water

C.

the condensation of vapour

D.

solidifying candle wax

Correct answer is A

No explanation has been provided for this answer.

965.

CO(g) + H\(_2\) O\(_{(g)}\) → CO\(_{2(g)}\) + H\(_{2(g)}\)
Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO\(_{2(g)}\), H\(_2\)O\(_{(g)}\) and CO\(_{(g)}\) in kJmol\(^{-1}\) are - 394, -242 and - 110 respectively.

A.

+ 262 KJ mol -1

B.

- 262 KJ mol -1

C.

+ 42 KJ mol -1

D.

- 42 KJ mol -1

Correct answer is D

\(\Delta H (formation) (CO_2) = -394\)

\(\Delta H (formation) (H_2 O) = -242\)

\(\Delta H (formation) (CO) = -110\)

\(X = \sum H_{P} ^{F} - \sum H_{R} ^{F}\)

= (-394+ 0) - (-110 - 242 )

= -394 +352

= - 42 kJmol\(^{-1}\)