In the cell represented as $Ni_{(s)}|Ni_{(1M)}^{2+}||Ag_{(1M)}^{+}|Ag_{(s)}$,the reducing agent is

If $6$ batteries are connected in series in a car,and each battery has a potential of $2 \ V$,what is the total voltage of the battery system (in $V$)?

What is a secondary cell? Give examples of it.

Given that
$E^o_{Ni^{2+} | Ni} = -0.25 \ V$
$E^o_{Cu^{2+} | Cu} = 0.34 \ V$
$E^o_{Ag^{+} | Ag} = 0.80 \ V$
$E^o_{Zn^{2+} | Zn} = -0.76 \ V$
Which of the following reactions under standard condition will not take place in the specified direction?

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 $0.10 \ M \ HCl$ to give $H_{2(g)}$.
$(II)$ When $A$ is added to a solution of the other metal ions,metallic $D$ is formed,but not $B$ or $C$.

Write a note on hydrogen-oxygen fuel cell.