4. Chemical bonding and molecular structure — Chemistry STD 11 Science — Question

$I.$ $1$ molecule of oxygen

$II.$ $1$ atom of nitrogen

$III.$ $1 \times {10^{ - 10}}$ $g$ molecular weight of oxygen

$IV.$ $1 \times {10^{ - 10}}$ $g$ atomic weight of copper

$(I)$ ${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l);$

$\Delta {H^o_{298\,K}} =  - 285.9\,kJ\,mo{l^{ - 1}}$

$(II)$ ${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(g);$

$\Delta {H^o_{298\,K}} =  - 241.8\,kJ\,mo{l^{ - 1}}$

The molar enthalpy of vapourisation of water will be.....$kJ\,mol^{-1}$