Question

Which Pair Of Compounds Are Isomers?

Answer 1

The Pair Of Compounds that Are Isomers are CH3COCH3 and CH3CH2CHO. The answer is number 4. Isomers have the same formula but different structures. In number 4, both compounds contains three carbon atoms, one oxygen and 6 hydrogen atoms that makes them isomers.

Answer 2

Answer:  $CH_3COCH_3$ and $CH_3CH_2CHO$

Explanation:

The compounds having similar molecular formula but different arrangement of atoms or groups in space are called isomers and the phenomenon is called as isomerism.  

$CH_3COCH_3$ and $CH_3CH_2CHO$ are functional isomers which have same molecular formula containing 3 carbon atoms, 6 hydrogen atoms and one oxygen atom each but different functional groups attached.

Rest compounds do not have similar molecular formulas.

Thus $CH_3COCH_3$ and $CH_3CH_2CHO$ are isomers.