WAEC Chemistry Past Questions & Answers - Page 64

316.

The position of equilibrium in a reversible reaction is affected by

A.

particle size of the reactants

B.

vigorous stirring of the reaction mixture

C.

presence of a catalyst

D.

change in concentration of the reactants

Correct answer is D

The position of equilibrium will shift under the effects of changes in temperature, pressure and concentration. 

317.

The following factors would contribute to environmental pollution except

A.

production of ammonia

B.

manufacture of cement

C.

photosynthesis

D.

combustion

Correct answer is C

Photosynthesis is the process of food-making in plants, it doesn't have any by-products that pose a threat to the environment. Infact, the plants use our waste product of respiration (Carbon dioxide) and uses it for the photosynthetic process and gives off oxygen as by-product.

318.

The most suitable substance for putting out petrol fire is

A.

water

B.

carbon(IV) oxide

C.

fire blanket

D.

sand

Correct answer is B

In order to extinguish a petrol fire, you have to cut off the oxygen. This can be done by using carbon dioxide gas to dilute the oxygen available and stop the burning.

319.

Stainless steel is an alloy comprising of

A.

Fe and C

B.

Fe and Ni

C.

Fe, C and Ni

D.

Fe, C and Al

Correct answer is C

Stainless steel comprises iron (Fe), chromium (Cr), manganese (Mn), silicon (Si), carbon (C) and, in many cases, significant amounts of nickel (Ni) and molybdenum (Mo).

320.

The valence electrons of \(_{12}Mg\) are in the

A.

3s orbital

B.

2p\(_{x}\)

C.

2s orbital

D.

1s orbital

Correct answer is A

\(_{12}Mg = 2, 8, 2\)

\(= 1s^{2} 2s^{2} 2p^{6} 3s^{2}\)