Assertion : Current stops flowing when E_Cell = 0.

Reason : Equilibrium of the cell reaction is attained.

(i) Both assertion and reason are true and the reason is the correct explanation of assertion.

We know, E_cell = E_cathode – E_anode

For reaction to be spontaneous, E_cell should have a positive value and Δ_rG_cell negative.

At equilibrium, E_cell = 0, as current stops flowing.

Or, E_cathode = E_anode

Hence, Current stops flowing when E_Cell = 0 because equilibrium of the cell reaction is attained.