Which solution is filled in a salt bridge?

The standard electrode potential of $Zn^{2+}/Zn$ is $-0.76\, V$ and that of $Cu^{2+}/Cu$ is $0.34\, V$. The emf $(V)$ and the free energy change $(kJ\, mol^{-1})$,respectively for a Daniell cell will be

In the electrochemical cell $H_{2(g)}, 1 \ atm \ | \ H^+_{(aq)}, 1 \ M \ || \ Cu^{2+}_{(aq)}, 1 \ M \ | \ Cu_{(s)}$,which of the following statements is true?

From a solution of $CuSO_4$,the metal used to recover copper is

The minimum voltage (in $V$) required to bring about the electrolysis of $1 \ M$ copper$(II)$ sulphate solution at $298 \ K$ is (Given $E^{\circ}_{Cu^{2+}/Cu} = 0.34 \ V$ and $E^{\circ}_{O_2/H_2O} = 1.23 \ V$)

Suggest two materials other than hydrogen that can be used as fuels in fuel cells.