Explanation:
the other 40% is used to power the 60% making it only capable of 60% efficiency
Answer is (c), the latent heat of fusion. That is by definition the heat that 1 kg of a substance must absorb to melt in the vicinity of its melting point.
Mater doesn't just appear or disappeared. Chemical elements are still there just the connections and how it combines changes.
So what goes into your chemical eqation must still exist after the change.
I believe that the correct answer you are looking for is the distance traveled