Question

For certain first order reaction m, 75% of the reaction complete in 30 min. How much time it require to complete 99.9% of the reaction?

• A. $150min$
• B. $100min$
• C. $90min$
• D. $300min$

Answer 1

Answer: (A)

Its a 1st order reaction, So

$\frac{t_{x\%}}{t_{y\%}}=\frac{\log \frac{100}{100-x}}{\log \frac{100}{100-y}}$

Here $x\%=75\%$ and $y\%=99.9\%$

Substituting the values, We get

$\frac{30}{t_y\%}=\frac{\log \frac{100}{100-75}}{\log \frac{100}{100-99.9}}$

$t_{y\%}=\frac{30}{0.2}=150min$