What amount of heat is liberated during the formation of one gram of He4\mathrm{He}^{4}He4 from deuterium H2\mathrm{H}^{2}H2 ? What mass of coal with calorific value of 30 kJ/g30 \mathrm{~kJ} / \mathrm{g}30 kJ/g is thermally equivalent to the magnitude obtained?