Question

An organic compound undergoes first order decomposition If the time taken for the $60 \%$ decomposition is $540 \,s$, then the time required for $90 \%$ decomposition will be is ______ s. (Nearest integer)
(Given: $\ln 10=2.3 ; \log 2=0.3$)

Answer 1

t2​t1​​=K1​ln0.1a0​a0​​K1​ln0.4a0​a0​​​
t2​540​=ln10ln410​​
t2​540​=log10log10−log4​
t2​540​=11−0.6​
⇒t2​540​=0.4
⇒t2​=0.4540​=1350sec

So, the answer is 1350.