965 amp current is passed through molten metal chloride for one minute and 40 seconds during electrolysis. The mass of metal deposited is 9 gm at the cathode. The valency of metal atom (at.wt = 27) is

$$\begin{gathered} \text{ Mass deposited }=\frac{\text{ Atomic weight }\times \mathrm{i}\times \mathrm{t}}{\mathrm{n}\text{ factor }} \\ \mathrm{metal} \mathrm{mass} \mathrm{deposited} =9 \mathrm{g} \\ \mathrm{time} = 1 \min 40 \sec . = 100\sec \\ \mathrm{Metal}\text{'}\mathrm{s} \mathrm{atomic} \mathrm{weight} \mathrm{is} \mathrm{equal} \mathrm{to} 27 \\ \text{ Current, i }=965 \mathrm{A} \\ \begin{array}{l}9=\frac{27\times 965\times 100}{\mathrm{n}\times 96500}\\ \mathrm{n}=3\end{array} \end{gathered}$$

Therefore, the correct option is B