11. The variation in the duration of the day and the night is due to earth’s

A. Rotation on its axis
B. Revolution around the sun
C. Inclination of an angle of 60(1/2) degrees
D. Both (A) and (B)

12. The sulfites are a mineral group that contain one or more metallic elements in combination with the sulfate compound ____

A. SO₃
B. SO₂
C. SO₄
D. SO

13. The term ‘flora’ in the context of natural vegetation refers to

A. Assemblage of plant species living in association with each other in a given environmental frame
B. Plants of a particular region or period, listed by species and considered as a group
C. A large tract covered by trees and shrubs and its administration for assessing economic benefits
D. Role played by species of animals in the maintenance of ecological balance

14. Which of the following is concerned with the study of characteristics, origin and development of landforms?

A. Ecology
B. Geography
C. Geology
D. Geomorphology

15. The soils common to the southeastern USA are called

A. Ultisols
B. Alfisols
C. Aridsols
D. Mollisols