The pressure of $H_2$ required to make the potential of $H_2$-electrode zero in pure water at $298 \ K$ is

The $emf$ of cell $Tl | Tl^+_{(0.001M)} || Cu^{2+}_{(0.01M)} | Cu$ is $0.83 \ V$ at $298 \ K$. It could be increased by:

If $Zn/Zn^{+2}$ electrode is diluted $100$ times,then the change in electromotive force will be:

If the $E^{\circ}_{cell}$ for a given reaction has a negative value,which of the following gives the correct relationships for the values of $\Delta G^{\circ}$ and $K_{eq}$ ?

At $298 \ K$,some standard electrode potentials are given below:

$Pb^{2+} / Pb$	$-0.13 \ V$
$Ni^{2+} / Ni$	$-0.24 \ V$
$Cd^{2+} / Cd$	$-0.40 \ V$
$Fe^{2+} / Fe$	$-0.44 \ V$

Metal rods $X$ and $Y$ are inserted into a solution containing $0.001 \ M$ $X^{2+}$ and $0.1 \ M$ $Y^{2+}$ at $298 \ K$ and connected by a conducting wire. This results in the dissolution of $X$. The correct combination$(s)$ of $X$ and $Y$ are,respectively:
(Given: Gas constant,$R = 8.314 \ J \ K^{-1} \ mol^{-1}$,Faraday constant,$F = 96500 \ C \ mol^{-1}$)
$(A) \ Cd$ and $Ni \ \ (B) \ Cd$ and $Fe \ \ (C) \ Ni$ and $Pb \ \ (D) \ Ni$ and $Fe$

What is the sign of $\Delta G^o$ and the value of $K$ for an electrochemical cell for which $E_{cell}^o = 0.80 \ V$?