Chapter 8

In the electrolysis of aqueous \(\mathrm{NaCl}\), what volume of \(\mathrm{Cl}_{2}(g)\) is produced in the time that it takes to liberate \(5.0\) liter of \(\mathrm{H}_{2}(\mathrm{~g})\) ? Assume that both gases are measured at STP. (a) \(5.0\) (b) \(2.50\) (c) \(7.50\) (d) \(10.0\)

How many grams of \(\mathrm{Cr}\) are deposited in the electrolysis of solution of \(\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3}\) in the same time that it takes to deposit \(0.54 \mathrm{~g}\) of \(\mathrm{Ag}\) in a silver coulometer arranged in series with the \(\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3}\) cell? \(\quad\) (Atomic weight : \(\mathrm{Cr}=52.0 ; \mathrm{Ag}=108\) ) (a) \(0.0866\) (b) \(0.0288\) (c) \(0.173\) (d) \(0.220\)

In the electrolysis of a CuSO \(_{4}\) solution, how many grams of Cu are plated out on the cathode in the time that it takes to liberate \(5.6\) litre of \(\mathrm{O}_{2}(\mathrm{~g})\), measured at \(\mathrm{STP}\), at the anode? (a) \(31.75\) (b) \(14.2\) (c) \(4.32\) (d) None of these

When molten lithium chloride (LiCl) is electrolyzed, lithiúm metal is formed at the cathode. If current efficiency is \(75 \%\) then how many grams of lithium are liberated when \(1930 \mathrm{C}\) of charge pass through the cell? (Atomic weight: \(\mathrm{Li}=7\) ) (a) \(0.105\) (b) \(0.120\) (c) \(0.28\) (d) \(0.240\)

The cost of \(2 \mathrm{Rs} / \mathrm{kWh}\) of operating an electric motor for 10 hours takes \(10 \mathrm{amp}\) at \(110 \mathrm{~V}\) is : (a) \(79200 \mathrm{Rs}\) (b) \(22000 \mathrm{Rs}\) (c) 220 Rs (d) \(22 \mathrm{Rs}\)

A \(1 \mathrm{M}\) solution of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is electrolyzed. Select right statement with products at anode and cathode respectively : Given : $$ \begin{aligned} 2 \mathrm{SO}_{4}^{2-} & \longrightarrow \mathrm{S}_{2} \mathrm{O}_{8}^{2-}+2 e^{-} ; E^{\circ}=-2.01 \mathrm{~V} \\ \mathrm{H}_{2} \mathrm{O}(l) & \longrightarrow 2 \mathrm{H}^{+}(a q)+1 / 2 \mathrm{O}_{2}(g)+2 e^{-} ; E^{\circ}=-1.23 \mathrm{~V} \end{aligned} $$ (a) concentration of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) remain constant; \(\mathrm{H}_{2}, \mathrm{O}_{2}\) (b) concentration of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) increases; \(\mathrm{O}_{2}, \mathrm{H}_{2}\) (c) concentration of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) decreases; \(\mathrm{O}_{2}, \mathrm{H}_{2}\) (d) concentration of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) remains constant; \(\mathrm{S}_{2} \mathrm{O}_{8}^{2-}, \mathrm{H}_{2}\)

Use of electrolysis is in : (a) Electrorefining (b) Electroplating (c) Both (a) and (b) (d) None of these

When a solution of \(\mathrm{AgNO}_{3}(1 \mathrm{M})\) is electrolyzed using platinum anode and copper cathode. What are the products obtained at two electrodes? Given : \(E_{\mathrm{Cu}^{2+}}^{\circ} \mathrm{Cu}=+0.34\) volt; \(\quad E_{\mathrm{O}_{2}, \mathrm{H}^{+} \mid \mathrm{H}_{2} \mathrm{O}}^{\circ}=+1.23\) volt \(; \quad E_{\mathrm{H}^{+} \mid \mathrm{H}_{2}}^{\circ}=+0.0\) volt; \(E_{\mathrm{Ag}^{+} \mid \mathrm{Ag}}^{\circ}=+0.8 \mathrm{volt}\) (a) \(\mathrm{Cu} \longrightarrow \mathrm{Cu}^{2+}\) at anode; \(\mathrm{Ag}^{+} \longrightarrow \mathrm{Ag}\) at cathode (b) \(\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{O}_{2}\) at anode; \(\mathrm{Cu}^{2+} \longrightarrow \mathrm{Cu}\) at cathode (c) \(\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{O}_{2}\) at anode; \(\mathrm{Ag}^{+} \longrightarrow \mathrm{Ag}\) at cathode (d) \(\mathrm{NO}_{3}^{-} \longrightarrow \mathrm{NO}_{2}\) at anode; \(\mathrm{Ag}^{+} \longrightarrow \mathrm{Ag}\) at cathode

Which of the following statements is correct about Galvanic cell ? (a) It converts chemical energy into electrical energy. (b) It converts electrical energy into chemical energy. (c) It converts metal from its free state to the combined state. (d) It converts electrolyte into individual ions.

The function of a salt bridge is to : (a) maintain electrical neutrality of both half cells (b) increase the cell potential at the positive electrode (c) decrease the cell potential at the negative electrode (d) eliminate the impurities present in the electrolyte