$3\;g$ of activated charcoal was added to $50\;mL$ of acetic acid solution $(0.06\;N)$ in a flask. After an hour it was filtered and strength of the filtrate was found to be $0.042\;N$ . the amount of acetic acid absorbed (per gram of charcoal) is :

Question

$\begin{array}{1 1} 18\;mg \\ 36\;mg \\ 42\;mg \\ 54\;mg \end{array} $