The surface tension of which of the following liquid is maximum at  ${20}^{\circ }\mathrm{C}$  is

Surface tension of ${\mathrm{H}}_2\mathrm{O}$ is maximum due to maximum hydrogen bonding in comparision to

${\mathrm{C}}_6{\mathrm{H}}_6,{\mathrm{CH}}_3\mathrm{OH},{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$ 

The order of H - bonding is

${\mathrm{H}}_2\mathrm{O}>{\mathrm{CH}}_3\mathrm{OH}>{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$ (Benzene does not form H - bond)