Among $Mg$,$Cu$,$Fe$,and $Zn$,the metal that does not produce hydrogen gas in reaction with hydrochloric acid is:

$Li$ occupies a higher position in the electrochemical series of metals as compared to $Cu$ since:

For the decomposition of $Al_2O_3$ at $500^{\circ}C$,the free energy change is $\frac{2}{3} Al_2O_3 \to \frac{4}{3} Al + O_2$,$\Delta G = +966 \ kJ \ mol^{-1}$. The potential difference required for the electrolytic reduction of $Al_2O_3$ at $500^{\circ}C$ is ........... $V$.

The correct order of reduction potentials of the following pairs is
$A.$ $Cl_2 / Cl^{-}$
$B.$ $I_2 / I^{-}$
$C.$ $Ag^{+} / Ag$
$D.$ $Na^{+} / Na$
$E.$ $Li^{+} / Li$
Choose the correct answer from the options given below.

For the reaction $Cr_2O_7^{2-} + I^- \to I_2 + Cr^{3+}$,if $E_{cell}^o = 0.79 \ V$ and $E_{Cr_2O_7^{2-}}^o = 1.33 \ V$,then $E_{I_2}^o = $ ............. $V$.

The $E^{0}_{Red}$ values for $P, Q, R$ and $S$ are $-2.90 \, V, +0.34 \, V, +1.20 \, V$ and $-0.76 \, V$ respectively. The decreasing order of their reactivity is: