Chemical Kinetics Ques 37
37. Half life of a first order reaction is $4 s$ and the initial concentration of the reactants is $0.12 M$. The concentration of the reactant left after $16 s$ is
[1999]
(a) $0.0075 M$
(b) $0.06 M$
(c) $0.03 M$
(d) $0.015 M$
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Answer:
Correct Answer: 37.(a)
Solution:
(a) $ t _{1 / 2}=4 s \hspace{10mm} T=16 $
$n=\frac{T}{t _{1 / 2}}=\frac{16}{4}=4 $
$A=A_o(\frac{1}{2})^{n}=0.12 \times(\frac{1}{2})^{4}=\frac{0.12}{16}=0.0075 M$
where $A_o=$ initial concentration &
$A=$ concentration left after time $t$.
BETA
