If there is no greenhouse effect, then the average temperature at surface of earth would have been

Options

A. `15^(@)C`
B. `-18^(@)C`
C. `-6^(@)C`
D. `10^(@)C`

Answer

B

Explanation

Greenhouse gases like `CO_(2), CH_(4) " and " CFCs` are essential for keeping the earth warm and hospitable. They prevent a substantial part of long wave radiations emitted by earth to escape into space, but these gases radiate a part of this energy back to the earth. This phenomenon is called greenhouse effect. Because of green house effect, the mean annual temperature of earth is `15^(@)C`. In its absence, it will fall to `-18^(@)C`.