Name the functional groups present in the following compounds:
(i) `CH_(3)-CH_(2)-CH_(2)-OH`
(ii) `CH_(3)-CH_(2)-CH_(2)-COOH`
(iii) `CH_(3)-CH_(2)-CHO`
(iv) `CH_(3)-CO-CH_(2)-CH_(3)`

Explanation

(i) `-OH(ol)`
(ii) `-COOH("oic acid")`
(iii) `-CHO(al)`
(iv) `-CO-` (one)