Question

The rate constant for the reaction A B is $2\times {10}^{-4}lt.mo{l}^{-1}mi{n}^{-1}.$The concentration of A at which rate of the reaction is \( (1/20) \times 10^{-5} \) M/sec. is

• A. 0.25 M
• B. $\left(1/20\right)\sqrt{5/3}$
• C. 0.5 M
• D. None of these

Answer 1

The correct option is B $\left(1/20\right)\sqrt{5/3}$

Unit of rate constant = $litmo{l}^{-1}mi{n}^{-1}$
It is a $2^{nd}$ order $r^{th}$ $R=K[A{]}^2\frac{1}{12}\times {10}^{-5}=2\times {10}^{-4}[A{]}^2\left[A\right]=\sqrt{\frac{1}{240}}=\frac{1}{20}\sqrt{\frac{5}{3}}$