Question

why prpanone was first ketone??

Answer 1

Actually the ketone group occurs in the middle of an organic compound.

One carbon is from ketone group and 2 other is from compound.
1 carbon is from ketone only.

It is mainly due to its structure that the simplest ketone is propanone.

Hope This helps You!

Answer 2

The functional group ketone always occur in the middle of a carbon compound. And hence the first compound being propanone.