JAMB Chemistry Past Questions & Answers - Page 344

1,716.

Leads is used for making bullets and lead shots because of its

A.

resistance to corrosion

B.

low melting point

C.

high density

D.

flexibility

Correct answer is C

Lead is used for making bullets and lead shots because of its high density.

1,718.
1,719.

The substance that is used in the steel industry for the removal of carbon, sulphur and phosphorus impurities from pig iron is

A.

oxygen

B.

chlorine

C.

nitrogen

D.

hydrogen

Correct answer is A

The substance used in the steel industry for the removal of carbon, sulphur, and phosphorus impurities from pig iron is oxygen. This process is called "oxidation" and it occurs when oxygen reacts with the impurities in the pig iron, which then form oxides that can be easily removed.

1,720.

The rate of a reaction usually decreases with a decrease in the concentration of reactants because

A.

kinetic energy decrease

B.

temperature increase

C.

speed increases

D.

reactants collision decrease

Correct answer is D

Decrease in the concentration of reactants reduces the number of molecules that acquire effective collisions, and consequently reduces the reaction rate.