18.0 g of water completely vapourises at 100°C and 1 bar pressure and the enthalpy change in the process is 40.79 kJ mol –1 . What will be the enthalpy change for vapourising two moles of water under the same conditions? What is the standard enthalphy of vapourisation for water?

Options

1. AEnthalpy change for vapourising two moles of water under the same conditions is +81.58 kJ and ∆ vap H = +40.79
2. BEnthalpy change for vapourising two moles of water under the same conditions is +69.58 kJ and ∆ vap H = +40.79
3. CEnthalpy change for vapourising two moles of water under the same conditions is +81.58 kJ and ∆ vap H = +45.79
4. DEnthalpy change for vapourising two moles of water under the same conditions is +69.58 kJ and ∆ vap H = +45.79