(a)(i) Internal structure of the Earth
(ii) Characteristics of the crust:
(i) It is made up of upper part to form the continent
(ii) It is made up of granite and contains minerals like silicon and aluminum hence called SIAL
(iii) Its density is 2.7
(iv) It also contains the lower part to form the ocean floor
(vi) It is made up of basalt rocks and contains minerals like silicon, iron and magnesium hence called SIMA
(vi) It has a density of 3.0
(b) Importance of hydrosphere to man include:
(i) Hydrosphere provides water for domestic and industrial uses
(ii) It also provides means of transportation
(iii) It provides food, e.g fish
(iv) It can help to generate electricity (H.E.P)