The standard enthalpy of combustion of ethanol is −1368 kJ mol⁻¹. How much heat is released when 2.3 g of ethanol is completely burned? [Molar mass of ethanol = 46 g mol⁻¹]

Moles of ethanol = 2.3 ÷ 46 = 0.05 mol. Heat released = 0.05 × 1368 = 68.4 kJ. Option A represents heat for 0.5 mol, option B is for 0.1 mol, and option D is for 2 mol — all common arithmetic errors.