Question

For a first order reaction $t_{0.75}$ is 1368 seconds.Therefore, the specific rate constant in $se{c}^{-1}$ is:

• A. ${10}^{-3}$
• B. ${10}^{-2}$
• C. ${10}^{-9}$
• D. ${10}^{-5}$

Answer 1

The correct option is A ${10}^{-3}$

For first order reaction, $t_{0.75}=2t_{0.50}=1368sec.$

Hence, $t_{0.50}=684sec.$

Also $k=\frac{0.693}{t_{0.50}}=\frac{0.693}{684}\approx {10}^{-3}se{c}^{-1}.$

Hence, option A is correct.