The molar heat of vaporisation $(\Delta \;H_{vap})$ for water is

Question

$\begin{array}{1 1} (a)\; 40.79 \;kJ/mol \\ (b)\; 31.0\; kJ/mol \\ (c)\; 59.0 \;kJ/mol \\ (d)\; 9.2 \;kJ/mol \end{array}$