JAMB Chemistry Past Questions & Answers - Page 180

898.

Which of the following would support the conclusion that a solid sample is a mixture?

A.

the solid can be ground to a fine powder

B.

the density of the solid is 2.25 g dm3

C.

the solid has a melting range of 300oC to 375oC

D.

the solid absorbs moisture from the atmosphere

Correct answer is C

No explanation has been provided for this answer.

899.

Consider the following exothermic reaction \(2SO_{2(g)} + O_{2(g)} = 2SO_{3(g)}\) . If the temperature of the reaction is reduced from 800ºC to 500ºC, and 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.

O2 gas becomes unreactive

Correct answer is C

reducing the temperature from 800ºc to 500ºc will favour forward reaction according to Le Chatelier's principle hence the concentration of \(SO_3\) increases.

900.

Pick out the correct statement

A.

Zin heated to redness reacts with steam to give oxygen and zinc oxide

B.

Zinc heated to redness reacts with steam to give oxygen and hydrogen

C.

Zinc does not react with hot or cold water

D.

Zinc reacts with hot water to form zinc oxide and hydrogen

E.

Zinc reacts very easily with cold water to give zinc oxide and hydrogen

Correct answer is D

No explanation has been provided for this answer.