Steam at 100 °C is allowed to condense at its boiling point, releasing exactly 72.0 kJ of energy into the surroundings. The molar enthalpy of vaporization of water at 100 °C is 40.7 kJ mol⁻¹. Approximately how many water molecules condensed? (Avogadro’s number = 6.02 × 10²³ mol⁻¹)
a) 7.2×1024
b) 1.1×1024
c) 4.3×1023
d) 1.3×1024