Is friction due to intermolecular attractive forces or repulsive ones. Since both friction and normal force are the components of contact forces, shouldn't friction be repulsive.
For a force that is directed perpendicular to a surface the designations “repulsive” and “attractive” have clear meaning. Repulsive is in the outward normal direction. Attractive is in the inward normal direction.
For a force that is directed parallel to a surface those designations lose meaning. Which direction is “attractive” parallel to a surface?
Friction can neither be attractive nor repulsive since those terms do not have meaning for forces parallel to a surface.