Q6 / 155 · WBJEE 2019 · Chemistry

The charge carried by 1 millimole of $M^{n+}$ ions is 193 coulombs. The value of $n$ is

  • A
    1
  • Correct answer
    B
    2
  • C
    3
  • D
    4

Solution

One millimole $=0.001 \mathrm{mol}$ i.e. $1 \times 10^{-3} \mathrm{mol}$ $\because 96500 \mathrm{C}$ is required for $1 \mathrm{mol}$ of electrons. $\therefore 193 \mathrm{C}$ give $\frac{193 \times 1}{96500}=0.002 \mathrm{mol},$ i.e. $2 \times 10^{-3} \mathrm{mol}$ of electrons. Thus, value of $n$ in $M^{n+}$ is $=\frac{0.002}{0.001}=2$ Hence, option (b) is the correct answer.

Hence, the correct answer is option: 'B'.

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