text: You would need to know the specific heat of coal to get this answer. Looking on the web, it looks like it is about 1.05 kJ/kg◦C. So you have 200◦C * 5000 g * 1.05 J/g◦C = 1050000 J. I'm assuming "c" is the answer, because you must've been given the specific heat of coal as part of the problem, and it was slightly different than the one I found online.