Compound (A) `C_(5)H_(8)O_(2)` liberated `CO_(2)` on reaction with sodium bicarbonate. It exists in two forms neither of which is optically active. It yielded compound (B) `C_(5)H_(10)O_(2)` on hydrogenation. Compound (B) can be separated into enantiomorphs. Write structures of (A) and (B).

Answer

(A) `CH_(3)-underset("cls")underset(CH_(3)-H)underset(||)(C)-COOH` `CH_(3)-underset("trans")underset(H-C-CH_(3))underset(||)(C)-COOH`
(B) `CH_(3).CH_(2).underset(CH_(3))underset(|)overset(H)overset(|)C-COOH` (2-methylbutanoic acid)