Electric current is passed through two cells $\text{'}\mathrm{A}\text{'}$ $\text{'}\mathrm{B}\text{'}$ in series. Cell$\text{'}\mathrm{A}\text{'}$ contains an aqueous solution of ${\mathrm{Ag}}_2{\mathrm{SO}}_4$ and platinum electrodes. The cell  $\text{'}\mathrm{B}\text{'}$ contains an aqueous solution of ${\mathrm{CuSO}}_4$ and $\mathrm{Cu}$ electrodes. The current is passed till $1.6 \mathrm{g}$ of oxygen is liberated at the anode of cell $\text{'}\mathrm{A}\text{'}.$

Calculate the quantities of substances deposited at the cathodes of the two cells.$(\mathrm{Ag}=108, \mathrm{Cu}=63.5)$

Give the answer up to two places of decimal.

Anthracene can be oxidised anodically to anthraquinone. What weight of anthraquinone can be produced by the passage of a current of $1 \mathrm{amp}$ for $60 \mathrm{minutes}$ if the current efficiency is $100\%?$

Give the answer up to two places of decimal.

To reduce nitrobenzene to aniline, $20 \mathrm{g}$ of ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NO}}_2, 30 \mathrm{cc}$ of an alcohol, $250 \mathrm{cc}$ of water, $11 \mathrm{g}$ of $\mathrm{HCl}$ and $1 \mathrm{g}$ of ${\mathrm{SnCl}}_2 . 2{\mathrm{H}}_2\mathrm{O}$ were placed in the cathode space. After passing current at a rate of $26.5 \mathrm{amp}/\mathrm{hour}$ through the lead cathode electrolytic cell, $12.76 \mathrm{g}$ of aniline was produced. Determine the current yield.

Most of the copper used to make wire has been electrically refined by depositing it from copper salts solution (divalent) on to a cathode. What is the cost of electrical energy required per $\mathrm{kg}$ of copper if, the cost of electricity is $\mathrm{Rs}. 0.25 \mathrm{per}$ $\mathrm{kWh}$ and the cell operates at $0.2 \mathrm{volt}$? The electrochemical equivalent of copper is $0·00033 \mathrm{g}/\mathrm{coulomb}.$

How long should a current of $0.5 \mathrm{amp}$ be passed through $50 \mathrm{mL}$ of a $0.10 \mathrm{M} \mathrm{NaCl}$ solution in order to make its $\mathrm{pH}=12$, assuming that no volume changes?

Round-off the answer to the nearest integer.

Lake Cayuga has a volume of water estimated to be $8.2\times {10}^{12}$ $\mathrm{L}$. A power station not so far above Cayuga's waters produces electricity at the rate of $1.5\times {10}^6$ $\mathrm{coulombs}$ $\mathrm{per} \mathrm{second}$ at an appropriate voltage. How long(in years) would it take to electrolyse the lake?

If the answer is $\mathrm{X}\times {10}^{\mathrm{y}}. \text{Give the value of} \mathrm{X} \text{up to one place of decimal.}$

$\mathrm{A} 200 -\mathrm{watt}, 110 -\mathrm{volt}$incandescent lamp is connected in series with an electrolytic cell of negligible resistance containing a solution of zinc chloride. What weight of zinc will be deposited from the solution on passing a current for $30 \mathrm{minutes}$?

$(\mathrm{Zn}=63·5; 1 \mathrm{Faraday}=96500 \mathrm{coulombs})$