Which solution is filled in a salt bridge?

Consider the Galvanic cell $Zn|ZnSO_4||CuSO_4|Cu$. The reaction at the cathode is

In the experiment set up for the measurement of $EMF$ of a half-cell using a reference electrode and a salt bridge,when the salt bridge is removed,the voltage

For the electrochemical cell,$M|M^{+}||X^{-}|X,$ given $E^{\circ}(M^{+}|M) = 0.44 \; V$ and $E^{\circ}(X|X^{-}) = 0.33 \; V$. From this data,one can deduce that:

Which of the following changes takes place at the positive electrode during the recharging of a lead accumulator?

In a fuel cell,$H_2$ and $O_2$ react to produce electricity. In this process,$H_2$ gas is oxidized at the anode and $O_2$ gas is reduced at the cathode. If $67.2 \ L$ of $H_2$ gas at $\text{STP}$ is consumed in $15 \ min$,what is the current produced (in $A$)?