Is Friction a Conservative Force?

Friction is non-conservative because the amount of work done by friction depends on the path. One can associate a potential energy with a conservative force but not with a non-conservative force.

What forces are conservative forces?

The most familiar conservative forces are gravity, the electric force (in a time-independent magnetic field, see Faraday's law), and spring force. Many forces (particularly those that depend on velocity) are not force fields.

Is friction conservative or dissipative?

Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from the system as the system progresses, energy that you can't get back.