JAMB Chemistry Past Questions & Answers - Page 97

481.
482.

Hydrogen is not liberated when trioxonitrate(v)acid reacts with zinc because

A.

zinx is not rendered passive by acid

B.

hydrogen produced is oxidized to water

C.

oxides of nitrogen are produced

D.

all nitrates are soluble in water

E.

trioxonitrate(v)acid is a strong acid

Correct answer is B

When metals react with nitric acid, hydrogen gas is liberated. Nitric acid is a very strong oxidizing agent. So , it oxidizes the hydrogen gas formed during the reaction to form water and an oxide of nitrogen.

\(Zn+4HNO_{3} \to Zn(NO_{3})_{2} + 2NO_{2} + 2H_{2}O\)

483.

A certain volume of gas at 298k is heated such that its volume and pressure are now four times the original values. What is the new temperature?

A.

18.6k

B.

100.0k

C.

298.0k

D.

1192.0k

E.

4768.0k

Correct answer is E

\(\frac{P_1V_1}{T_1} = \frac{4P_1 \times 4V_1}{T_2}\)

i.e \(\frac{P_1V_1}{298} = \frac{4P_1 \times 4V_1}{T_2}\)

T2 = \(\frac{298 \times 4P_1 \times 4V_1}{P_1V_1}\)

= 298 + 16 = 4768.0k