Among the following metals,the strongest reducing agent is

If the standard reduction potentials of four electrodes $A$, $B$, $C$, and $D$ are $+2.5 \text{ V}$, $+3.0 \text{ V}$, $-2.0 \text{ V}$, and $-1.5 \text{ V}$ respectively, in which case is the standard $emf$ of the cell maximum?

The standard reduction electrode potentials of four elements are:
$A = -0.250 \ V$,$B = -0.136 \ V$,$C = -0.126 \ V$,$D = -0.402 \ V$
The element that displaces $A$ from its compounds is:

The $(\frac{\partial E}{\partial T})_P$ of different types of half cells are as follows:

$A$	$B$	$C$	$D$
$1 \times 10^{-4}$	$2 \times 10^{-4}$	$0.1 \times 10^{-4}$	$0.2 \times 10^{-4}$

(Where $E$ is the electromotive force)
Which of the above half cells would be preferred to be used as reference electrode?

For the following cell reaction,$Ag | Ag^{+} | AgCl | Cl^{-} | Cl_2, Pt$
$\Delta G_f^{\circ}(AgCl) = -109 \ kJ/mol$
$\Delta G_f^{\circ}(Cl^{-}) = -129 \ kJ/mol$
$\Delta G_f^{\circ}(Ag^{+}) = 78 \ kJ/mol$
$E^{\circ}$ of the cell is

The value of $x$ from the given data is