JAMB Chemistry Past Questions & Answers - Page 22

106.

An organic functional group which can likely decolorize ammoniacal silver nitrate is?

A.

alkene

B.

alkane

C.

alkyne

D.

alkanol

Correct answer is C

Terminal alkynes react with Tollens reagent (ammoniacal silver nitrate solution) to form silver alkynides as a white precipitate, whereas internal alkynes do not react with Tollens reagent.

107.

Zn + 2HCL → ZnCl\(_2\) + H\(_2\) 

What happens to zinc in the above reaction?

A.

oxidized

B.

a reactant

C.

reduced

D.

a metal

Correct answer is A

-Zn is a reducing agent, HCl is an oxidizing agent.

-the zinc is oxidized

108.

N\(_2\)O\(_4\) ⇔ 2NO\(_2\)          (Δ = -ve)

From the reaction above, which of these conditions would produce the highest equilibrium yield for N\(_2\)O\(_4\)?

A.

Low temperature and high pressure

B.

Low temperature and low pressure

C.

high temperature and low pressure

D.

high temperature and high pressure

Correct answer is D

high temperature and high pressure favor the highest yield for N\(_2\)O\(_4\)

high temperature favours the production of the reactant since it is endothermic, while high pressure favours the side involving a decrease in volume.

109.

An organic compound with fishy smell is likely to have a general formula?

A.

RCONHR\(^1\)

B.

RCONH\(_2\)

C.

RNH\(_2\)

D.

RCOR\(^1\)

Correct answer is C

Amines possess a characteristic ammonia smell, liquid amines have a distinctive "fishy" and foul smell. 

-Amine. R-NH2

110.

Using the metal activity series, the metal that can liberate hydrogen gas from steam is?

A.

iron

B.

copper

C.

tin

D.

lead

Correct answer is A

Iron reacts with steam to form iron oxide and hydrogen gas.