These two molecules are structural isomers. What is the difference between them?
A)the number of carbon atoms
B)the number of hydrogen atoms
C)the location of a double-bonded oxygen atom
D)Only one of them has a double bond between carbon atoms.

Question

These two molecules are structural isomers. What is the difference between them? 
A)the number of carbon atoms 
B)the number of hydrogen atoms 
C)the location of a double-bonded oxygen atom 
D)Only one of them has a double bond between carbon atoms.

Quizplus · Accepted Answer

The two molecules are likely to be an example of a ketone and an aldehyde. The difference between a ketone and an aldehyde is that the carbonyl group (C=O) in an aldehyde molecule is always found at the end of a carbon chain, whereas the carbonyl group in ketone molecule may not be at the end of the chain. This means that the location of the double-bonded oxygen atom is different between the two molecules, making them structural isomers. The number of carbon and hydrogen atoms may be the same in the two molecules. Option D is incorrect, since both molecules likely contain a carbonyl group and therefore a double bond between carbon and oxygen.

These Two Molecules Are Structural Isomers