Good responses were given by many candidates. Few fumbled due to their failure to relate cohesion and adhesion forces with molecules of mercury and glass.
The expected answers are:
Mercury does not wet glass because (force of) cohesion/attraction of mercury molecules is greater than (force of) adhesion/attraction between glass and mercury molecules.
Water wets glass because (force of) adhesion/attraction between glass and water molecules is greater than (force of) cohesion/attraction of water molecules.