Question:
For a first order reaction, the ratio of the time for $75 \%$ completion of a reaction to the time for $50 \%$ completion is (Integer answer)
Solution:
$k=\frac{2.303}{t} \log \frac{a}{a-x}$
$\frac{2.303}{t_{50 \%}} \log \frac{100}{100-50}=\frac{2.303}{t_{75 \%}} \log \frac{100}{100-75}$
$\mathrm{t}_{75 \%}=2 \mathrm{t}_{50 \%}$