JAMB Chemistry Past Questions & Answers - Page 108

536.

PCL5(g)= PCL3(g) + Cl2(g)

In the reaction above, a decrease in pressure will

A.

Decelerate the reaction

B.

Increase yield of Pcl3

C.

Increase the yield of Pcl5

D.

Accurate the reaction

Correct answer is B

If we decrease the pressure in the reaction, there will be rapid breakage spilling of pcl5. And these follows a principle that molecule of gases tends to move from a region of higher pressure to low pressure. Option A,C,D will not be affected by pressure decrease

537.

According to the kinetic theory an absence in temperature causes the kinetic energy of particles to

A.

decrease

B.

increase

C.

remain constant

D.

be zero

Correct answer is D

No explanation has been provided for this answer.

538.

The furring of kettles is caused by the presence of what compound in water?

A.

calcium tetraoxosulphate (IV)

B.

calcium hydrogentrioxocarbonate (IV)

C.

calcium hydroxide

D.

calcium trioxocarbonate (IV)

Correct answer is D

Calcium hydrogen carbonate, often present in temporary hard water, is boiled in a kettle to remove the hardness. In the process, a scale forms on the inside of the kettle in a process known as furring of kettles. This scale is composed of calcium carbonate.

539.

Which of the following results in the fall of acid rain?

A.

oxide of lead

B.

particulate matter

C.

oxides of sulphur

D.

gaseous hydrocarbon

Correct answer is C

Oxide of sulphur is formed as a result of acid rain. Options A,B, D are not formed as a result of the pressure of acid

540.

NH3(g) + HCl(s) → NH 4Cl (s)

The entropy change in the system above is

A.

positive

B.

zero

C.

negative

D.

intermediate

Correct answer is C

Entropy s is a measure of the degree of disorder or randomness of a substance. The entropy charge in the system is negative. Options B, C, D will not give negative but the result into positive