Question

For a first order reaction, $(A)\to $ product. Concentration of $A$, changes from $0.1\, M$ to $0.025 \,M$ in $40$ minutes the rate of reaction of when concentration of $A$ is $0.01 \,M$ is :

• A. $3.47\times10^{-4} M /min^{-1}$
• B. $3.47\times10^{-5} M /min^{-1}$
• C. $1.73\times10^{-4} M /min^{-1}$
• D. $1.73\times10^{-5} M /min$

Answer 1

Answer: (A)

For first order reaction,
$k=\frac{2.303}{t} log\frac{a}{a-x}=\frac{2.303}{40}log\frac{0.1}{0.025}=3.46\times10^{-2}$
Rate= $[k]A=3.46\times10^{-2}\times0.01=3.46\times10^{-4}$