Question

Match the rate law given in column I with the dimensions of rate constants given in column II and mark the appropriate choice.

Column I		Column II
$(A)$	Rate $=k[N{H}_3{]}^0$	(i)	$mol{L}^{-1}{s}^{-1}$
(B)	Rate $=k[H_2{O}_2][I^{-}]$	(ii)	$Lmo{l}^{-1}{s}^{-1}$
(C)	Rate $=k[C{H}_{3}CHO{]}^{3/2}$	(iii)	$s^{-1}$
(D)	Rate$=k[C{}_2{H}_{5}Cl]$	(iv)	$L^{1/2}mo{l}^{-1/2}{s}^{-1}$

• A. $(A)\to (iv),(B)\to (iii),(C)\to (ii),(D)\to (i)$
• B. $(A)\to (i),(B)\to (ii),(C)\to (iii),(D)\to (iv)$
• C. $(A)\to (ii),(B)\to (i),(C)\to (iv),(D)\to (iii)$
• D. $(A)\to (i),(B)\to (ii),(C)\to (iv),(D)\to (iii)$

Answer 1

Answer: (D)

(A) Rate $=k{\left[N{H}_3\right]}^0$
It is zero order reaction.
$\therefore$ Units of rate constant are same as rate.
i.e $mol{l}^{-1}{s}^{-1}$
(B) Rate $=k{\left[H_2{O}_2\right]}^1{\left[I^{-}\right]}^1$
It is second order reaction as order $=1+1=2$
$\therefore$ Units of Rate constant are $Lmo{l}^{-1}{s}^{-1}$
(C) Rate $=k{\left[C{H}_{3}CHO\right]}^{3/2}$
It is fractional order reaction with order $=\frac{3}{2}$
$\therefore$ Units of rate constant are $L^{\frac{1}{2}}mo{l}^{-\frac{1}{2_s^{-1}}}$
(D) Rate $=k{\left[C_2{H}_{5}Cl\right]}^{-1}$
It is first order reaction. So units of rate constant are $s^{-1}$