Question

How many carbon atoms are present in one molecule of the first members of ketone?

Answer 1

First member of ketone functional group is propanone. It is also known as acetone.

CH3-C-CH2
..........||
.........O

The prop suffix is used when we have three carbon atoms.
Therefore, first member of ketone has 3 carbon atoms.
Note: Please ignore the dots in the structure of propanone given above.

Thanks.

Answer 2

the answer is three propanone