What do you mean by sink? Give one example

(i) What do you mean by sink? Give one example.
(ii) What is the sink for hydrocarbons and why?

(i) Medium present in the environment that take up some amount of certain pollutants is called sink e.g., oceans act as siilk for ${{SO}{2}}$,
${{CO}
{2}}$ and
${{NO}_{2}}$.
(ii) Chemical and photochemical reactions act as sink for hydrocarbons as these get decomposed in these reactions.