N₂ is obtained by the decomposition of benzene diazonium chloride at constant temperature. It is a first - order reaction the various volumes obtained at different time intervals are as    

Time (min)	0	20	50	70	$\infty$
N2(mL)	0	10	25	32	162

The rate constant of the reaction is

detailed solution

Correct option is B

Decomposition of benzene diazonium chloride occur the following manner.C6H5N=NCl⟶C6H5Cl+N2The volume of nitrogen obtained shows the extent of decomposition of benzene diazonium chloride so   a∝V∞=162mL(a−x)∝V∞−VtmLFor first order reaction, k=2.303tlog10V∞−V0V∞−Vtor                                   k=2.303tlog10V∞V∞−Vl                    ∵V0=0At 20 min                     k=2.30320log10162162−10                                         =2.30320log10162152=3.18×10−3min−1≈3.2×10−3min−1