Question

Statement(A): For green house effect, presence of green plants is essential.
Statement (R): $C{O}_2$ and water vapour present in the atmosphere absorb the re-emitted IR radiation from the earths surface and warm the air.

• A. Both A and R are true and R is the correct explanation of A.
• B. Both A and R are true but R is not correct explanation of A.
• C. A is true and R is false
• D. A is false and R is true.

Answer 1

Answer: (D)

A is false and R is true.

Greenhouse effect
* The progressive heating up of surface of the earth is earth is called green house effect or global warming.
* $C{O}_{2}and{H}_{2}O$ block a part of the heat (IR) emitted by the earth & reflect back. Due to this earth surface gets heated up.
* 50% in $C{O}_2$ content of air can increase the surface temperature of the earth by $3^o$C.
* In addition to $C{O}_2$ , the other green - house gases are CFCs (17%), $O_3$ (18%), NO (4%), water vapour (2%).