100g of water (specific heat=4.184J/g*C) and 100g of a metal sample (specific heat = 0.397J/g*C) are heated from 25C to 75C. Which substance required more thermal energy to reach 75C? (Explain your reasoning) ...?

I believe that water would require more thermal energy in order to reach a temperature of 75°C. It is because it has a higher value of specific heat which would mean that for every change of 1 degrees celsius it requires a higher amount of energy input. Hope this answers the question.