Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

921.

In what respect will two dry samples of nitrogen gas differ from each other if sample 1 is prepared by completely removing CO2 and O2 from air, and sample 2 is prepared by passing purified nitrogen(i)oxide over heated copper? sample 1 is

A.

purer than sample 2

B.

slightly denser than sample 2

C.

in all respects the same as sample 2

D.

colourless but sample 2 has a light brown colour

E.

slightly less reactive than sample 2

Correct answer is B

No explanation has been provided for this answer.

922.
923.

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.

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

924.

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