Energy that is 'lost" to heat, has merely been converted to another form, not
lost forever.

if the heat energy is wasted, then, energy is lost forever.

Explanation: According to conservative of energy, which state that energy is neither created nor destroyed but only convert from one form to another.

The energy which should have been used in one form has been converted to heat energy which could have been used for for thing or the other, if there is nothing the heat energy can be used for, then the energy is wasted. This is tantamount to being lost forever.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures