• # question_answer Select the molecule which has only one $\pi -\text{bond}$ [Pb. PMT 1998] A) $CH\equiv CH$ B) $C{{H}_{2}}=CHCHO$ C) $C{{H}_{3}}CH=C{{H}_{2}}$ D) $C{{H}_{3}}CH=CHCOOH$

a. $\underset{2\pi -\text{bonds}}{\mathop{H-C\equiv C-H}}\,$ b. $\underset{2\pi -\text{bonds}}{\mathop{C{{H}_{2}}=CH-\underset{H}{\mathop{\underset{|}{\mathop{C}}\,}}\,=O}}\,$ c.$\underset{1\pi \text{ bond}}{\mathop{C{{H}_{3}}CH=C{{H}_{2}}}}\,$      d. $\underset{2\pi -\text{bonds}}{\mathop{C{{H}_{3}}-CH=CH-}}\,\underset{O}{\mathop{\underset{|\,|}{\mathop{C}}\,}}\,-OH$