\(\frac{540}{ t _2}=\frac{\ln \frac{10}{4}}{\ln 10}\)
\(\frac{540}{ t _2}=\frac{\log 10-\log 4}{\log 10}\)
\(\frac{540}{ t _2}=\frac{1-0.6}{1}\)
\(\Rightarrow \frac{540}{ t _2}=0.4\)
\(\Rightarrow t _2=\frac{540}{0.4}=1350\,sec\)
(આપેલું છે: $R =2\,cal\,K ^{-1}\,mol ^{-1}$ )