16. Of the following atmospheric gases, there is one whose percentage volume is not
influenced by human activities. Identify it.
a) Ozone
b) Methane
c) Carbon dioxide
d) Oxygen

l7.A climax vegetation l which its characteristic reflect the influence of human
activities is considered as:
a)-C1imatio climax
b) Sub-climax
c) Plagio-climax
d) Mono-climax

18.Which ofthe following soil pH values is suitable for agriculture?
a) 1—4
b) 5—7
0) 6—8

d) 9 _ 11

19. A process by which sand and rocks particles are carried by wind in desert is lasted against rock outcrop resulting in catching and removal of particles is called:

a) Attrition 

b) Abrasion

c) Corrosion

d) Deflation

20.Which of the following is the dominant texture of a soil in a region dominated by high-intensity physical weathering?

a) Clay

b) Sand

c) Silt