Question

For a first order reaction $t_{0.75}$ is 1386 s. Therefore, the specific rate constant is:

• A. ${10}^{-1}{s}^{-1}$
• B. ${10}^{-2}{s}^{-1}$
• C. ${10}^{-3}{s}^{-1}$
• D. none of these

Answer 1

The correct option is C ${10}^{-3}{s}^{-1}$

As we know,

$t_{0.75}=2t_{1/2}$

$\therefore t_{1/2}=\frac{1386}{2}=693s$

$k=\frac{0.693}{693s}={10}^{-3}{s}^{-1}$