JAMB Chemistry Past Questions & Answers - Page 435

2,171.

Consider the following equation H2O + 2Fe2+ + Cl2 ↔ 2Fe3+ + 2Cl- + H2O. Which behaves as an oxidizing agent?

A.

Fe2+

B.

Cl2

C.

Fe3+

D.

Cl-

E.

H2O

Correct answer is B

- An oxidizing agent is a substance that causes oxidation by accepting electrons; therefore, it gets reduced. A reducing agent is a substance that causes reduction by losing electrons; therefore it gets oxidized.

- Common examples of oxidizing agents include halogens (such as chlorine and fluorine)

2,172.

Two gas cylinders contain ethylene (ethene) and acetylene respectively. One test which can be used to distinguish between them is by?

A.

passing each gas through bromine water

B.

passing each gas through dilute potassium permanganate solution

C.

passing each gas through silver nitrate solution

D.

treating each gas catalytically with excess hydrogen gas

Correct answer is C

Acetylene reacts with ammoniacal AgNO3 solution to form a white precipitate of silver acetylide (AgC-=Cag) but ethylene does not

2,173.

Three solutions contain carbonate, sulphate and sulphide ions respectively. One test that will identify just ONE of them completely is by addition to each of them of

A.

barium chloride solution

B.

dilute hydrochloric acide

C.

lead nitrate solution

D.

calcium chloride solution

E.

sodium hydroxide solution

Correct answer is C

No explanation has been provided for this answer.

2,174.

If excess zinc is added to a bluish green solution of copper (II) sulphate, and the excess zinc filtered off after completion of reaction, a colourless solution is obtained because

A.

both zinc and copper are metals

B.

the sulphate radical and the zinc ion are divalent

C.

zinc is more electropositive than copper

D.

both zinc and copper form depositive ions in solution

E.

zinc is a reducing agent

Correct answer is C

No explanation has been provided for this answer.

2,175.

Consider the following exothermic reaction
2SO2(g) + O2(g) ↔ 2SO3(g)
If the temperature of the reaction is reduced from 800°C to 500°C, an no other change takes place, then

A.

the reaction rate increases

B.

concentration of SO3 decreases

C.

concentration of SO3 increases

D.

SO2 gas becomes unreactive

E.

O3 gas becomes unreactive

Correct answer is C

No explanation has been provided for this answer.