Answer the correct option with full explanation urgently Very important.

Dear Student,
Let the white ring of NH4Cl forms at time t and the distance diffused by NH3 in time t be x cm. Thus, by HCl would be (100-x)cm

$dis\tan ce of diffusion = rate of diffusion \times time$
$$\begin{gathered} rate of diffusion, r = \frac{1}{\sqrt{M}}, where M is the molar mass \\ Thus, \\ Rate of diffusion of N{H}_3: r_{N{H}_3} =\frac{1}{\sqrt{M_{N{H}_3}}}=\frac{1}{\sqrt{17}} \\ Rate of diffusion of HCl: r_{HCl} =\frac{1}{\sqrt{M_{HCl}}}=\frac{1}{\sqrt{36.5}} \\ \frac{diffusion length of N{H}_3 in time t}{diffusion length of HCl in time t}=\frac{d_{N{H}_3}}{d_{HCl}}=\frac{\sqrt{M_{HCl}}}{\sqrt{M_{N{H}_3}}} \\ \frac{x}{100-x}=\sqrt{\frac{36.5}{17}} \\ \frac{x}{100-x}=1.465 \\ x=146.5-1.465x \\ 2.465x=146.5 \\ x=\frac{146.5}{2.465}=59.43cm\approx 60cm \end{gathered}$$
Ans (B) Near HCl cotton plug.

Regards