$A$ moving coil galvanometer has $150$ equal divisions. Its current sensitivity is $10 \text{ divisions per milliampere}$ and voltage sensitivity is $2 \text{ divisions per millivolt}$. In order that each division reads $1 \text{ V}$,the resistance in ohms needed to be connected in series with the coil will be

Write a note on the $Ni-Cd$ cell.

Give the uses of the mercury cell.

The standard free energy change $($ in $J)$ for the reaction $3 Fe^{2+}_{(aq)} + 2 Cr_{(s)} \rightleftharpoons 2 Cr^{3+}_{(aq)} + 3 Fe_{(s)}$ given $E_{Fe^{2+}/Fe}^{\circ} = -0.44 \, V$ and $E_{Cr^{3+}/Cr}^{\circ} = -0.74 \, V$ is $(F = 96500 \, C)$.

For the reduction of silver ions with copper metal,the standard cell potential was found to be $+ 0.46 \ V$ at $25^oC.$ The value of standard Gibb's energy,$\Delta G^o$ will be .......... $kJ.$
$(F = 96500 \ C \ mol^{-1})$

An aqueous solution of hydrazine $(N_2H_4)$ is electrochemically oxidized by $O_2$,thereby releasing chemical energy in the form of electrical energy. One of the products generated from the electrochemical reaction is $N_{2(g)}$.
Choose the correct statement$(s)$ about the above process:
$A$. $OH^{-}$ ions react with $N_2H_4$ at the anode to form $N_{2(g)}$ and water,releasing $4$ electrons to the anode.
$B$. At the cathode,$N_2H_4$ breaks to $N_{2(g)}$ and nascent hydrogen released at the electrode reacts with oxygen to form water.
$C$. At the cathode,molecular oxygen gets converted to $OH^{-}$.
$D$. Oxides of nitrogen are major by-products of the electrochemical process.