Question

The cost of electricity required to deposit $1$ g of magnesium is Rs. $5.00$. How much would it cost to deposit $10$ g of aluminium?

• A. Rs. $10.00$
• B. Rs. $27.00$
• C. Rs. $44.44$
• D. Rs. $66.67$

Answer 1

Answer: (D)

Rs. $66.67$

$M{g}^{2+}+2e^{-}\to Mg$
$1gofMg=\frac{1}{24}moleofMg$
$\therefore Amountofelectricity=\frac{1}{24}\times 2electricity$

$\therefore \frac{1}{24}mole{e}^{-}costsRs5$
$\therefore 1mole{e}^{-}costs=Rs5\times 12=60$

$10gAl=\frac{10}{27}moleofAg$

$A{l}^{3+}+3e^{-}\to Ag$
$\therefore moleof{e}^{-}used=\frac{10\times 3}{27}=\frac{30}{9}mole$

$\therefore costofelectricity=\frac{10\times 60}{9}=\frac{600}{9}=Rs66.67$.

Hence, option D is correct.