51. The layer of the earth, immediately below the crust, is called

A. outer core
B. inner core
C. inner mantle
D. outer mantle

52. The highest mountains in Africa, which is not part of any mountains chain, is

A. Mt. Aconcagua
B. Mt. Kilimanjaro
C. Mt. Kosciuszko
D. Mont Blanc

53. The heavier silicates named as ‘Sima’ or silica + magnesium are most abundant in the

A. crust
B. core
C. mantle
D. ocean floors

54. The imaginary line on the earth’s surface, which closely follows the 180 º meridian, is called the

A. International Date Line
B. Tropic of Cancer
C. Equator
D. Prime Meridian

55. The largest part of our hydrosphere is

A. Atlantic Ocean
B. Indian Ocean
C. Pacific ocean
D. Antarctica ocean