$A$ negative $e.m.f.$ for a cell represents:

Which reactions are possible due to electro-chemistry in human brain?

Calculate the $K_C$ and $\Delta G^o$ for the chemical reaction :
$Ni_{(s)} + 2Ag_{(aq)}^{+} \to Ni_{(aq)}^{2+} + 2Ag_{(s)}$ $ [E^o = 1.05 \, V] $

Given ${E^o}_{Ag^{+}/Ag} = 0.80 \ V$,${E^o}_{Mg^{2+}/Mg} = -2.37 \ V$,${E^o}_{Cu^{2+}/Cu} = 0.34 \ V$,${E^o}_{Hg^{2+}/Hg} = 0.79 \ V$.
Which of the following statements is correct?

Based on the following information,arrange four metals,$A$,$B$,$C$,and $D$,in order of increasing ability to act as reducing agents:
$(I)$ Only $C$ reacts with $1 \ M \ HCl$ to give $H_{2(g)}$.
$(II)$ When $A$ is added to a solution of the other metal salts,metallic $D$ is formed,but not $B$ or $C$.

$1000 \, mL$ of $1 \, M$ $CuSO_{4(aq)}$ is electrolysed by $9.65 \, A$ current for $100 \, s$ using $Pt$ electrodes. Which statement is incorrect?