Account the following

Account for the following
(i) Ozone layer is necessary for life.
(ii) The temperature of thermosphere is 1500°C but a person would not feel warm in it.
(iii) Increased ${{SO}{2}}$ concentration causes chlorosis.
(iv) ${{CO}
{2}}$ keeps the earth warm.
(v) The pH of normal rain water is 5.6.

(i) Ozone absorbs about 99% of harmful UV radiations coming from the sun and thus protects human being from adverse effect of UV radiations. Thus, its presence is necessary for life.
(ii) This is because the pressure in the thermosphere is very low.
(iii) Because increased ${{SO}{2}}$ concentration retards the rate of formation of chloroplast.
(iv) ${{CO}
{2}}$ have tendency to absorb most of the heat radiation that are emitted by objects of the earth. Thus, it keeps the earth warm.
(v) This is because of the dissolution of ${{CO}{2}}$ from atmosphere which furnish H+ ions to the rain water.
$H { 2 }O$ +
{2}}$ -------->

$H_{2}CO_{3}$ ----------> ${{H}^{+}}$ +