Question

A good source of energy would be one which would do a small amount of work
per unit volume of mass. (Correct the mistakes, if any)

Answer 1

Answer:

A good source of energy would be one which would do a large amount of work per unit volume or mass

Answer 2

Answer:

Explanation:

A good source of energy would be one which would do a small amount of work  per unit volume of mass. - Incorrect

A good source of energy is the one which would do a large amount of work per unit volume or mass. - Correct

When we want to use something, we give it feedback and we want a lot of output from that thing and of course we want a lot of output or work done by that thing, not a small amount of output or work done.