Question

If the half life of a first order reaction is 60 min, the approximate time in min, required to complete 90% of the reaction is $(log2=0.3)$

• A. $200$
• B. $240$
• C. $50$
• D. $100$

Answer 1

Answer: (B)

$240$

$\begin{array}{c}{t}_{\frac{1}{2}}=60min\\ 100\to 50\to 25\to 12.5\\ 60\to 120\Rightarrow 180\to 240min\\ Afterapprox240minthereactionwillbe{90}^{0}completed.\\ Hence,optionBiscorrectanswer.\end{array}$