Question

mercury is the only metal present in liquid state. can we use it as electrolyte?

Answer 1

generally, metals basic character is conductivity either it may be in solid state or it may be liquid state.this is because they have conduction electrons means metals have unpaired electrons in their valency shell.
             so mercury can also be used as electrolytes

Answer 2

Yes.It can be used as a electrolyte for the preparation or purification of sodium and chlorine.