Explanation

(a) Two main types of environmental pollution are:

(i) Air pollution

(ii) water pollution

Three causes of water pollution include:

(I) The release of disease-producing (pathogenic) bacteria and viruses (biological pollution diseases

(ii) Undesirable ions and compounds in solution (chemical pollution) into water thereby changing its colour, taste and/or smell

(iii) Oil spillage - the bursting of oil pipes results in oil spillage into water thereby changing the colour, taste and smell of the water.

(b) Three effects of pollution on man are:

(i) Atmospheric pollution, which may be caused by fog reduces visibility. This poses a serious danger to motorists and pilots

(ii) Pollutants may have adverse psychological effects on man and animals e.g discomfort, chronic diseases, such as lung cancer and asthma, impairment of growth and death

(iii) Some pollutants are toxic and can kill plants e.g sulfur dioxide and hydrogen fluoride are toxic to plants from which man gets his food.

Correct Answer: C. Terrain to the south is less rugged

Correct Answer: D. cellophane

Correct Answer: C. underground water in limestone

Explanation

(b) Four ways in which the forest vegetation contributes to the economy of the country are:

(i) Provision of timber for construction of houses and furniture

(ii) Provision of foreign exchange earnings from the export of timber

(iii) Forest vegetation provides jobs to many people, e.g forest guards, lumbermen

(iv) Forest vegetation also provides medicinal herbs for the pharmaceutical industries.

(c) Four problems associated with exploitation of forest vegetation include:

(i) Heterogeneous nature of trees

(ii) Lack of motorable roads

(iii) High cost of survey to determine economic trees

(iv) Felling of timber is risky as many people have lost their lives in the process

Correct Answer: D. Zambia

Correct Answer: A. 14°C

Correct Answer: A. earth's inclination to the sun and its revolution

Correct Answer: D. soil profile

Explanation

Core:Innermost layer, about 3476km wide all round, consists largely of iron and nickel, divisible into inner and outer core, found in a molten state, reservoir of minerals to the other zones.

Mantle: middle layer, surrounds the core, about 2897km thick, composed of very dense rocks, rocks are rich in olivine basalt.

Crust:Lies above the mantle, outer layer, consists of granitic and basaltic rocks, varies in thickness from place to place , divisible into 2-sial and sima, forms soil, sustains life.