71.
Which of the following chemical materials is responsible for the depletion of ozone layer in the atmosphere ?

72.
Nitrogen fixation is a process of

73.
Greenhouse effect is caused by

74.
The lowest layer of earth's atmosphere is

75.
Earth’s atmosphere is an envelope of gases extending to a height of

76.
Depletion of ozone layer causes

77.
Nitrification is the biological process of converting

79.
The greenhouse effect is caused by the higher level of which gas in the atmosphere ?

80.
The atmospheric gas that is mainly responsible for green house effect :