A flask is filled with equal moles of A and B . The half lives of A and B are 100   s and 50   s…

A flask is filled with equal moles of A and B. The half lives of A and B are 100 s and 50 s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is____s.
(Given : ln2=0.693)

Solution

For first order reaction

k=0.693t12

A=4B

A0e-kAt=4B0e-kBt

as A0=B0;e-kAt=4e-kBt

-kAt=ln4-kBt

 tkB-kA=2ln2

t=2×0.6930.69350-0.693100=2×1002-1=200sec

Asked in: JEE Main 2022 (26 Jun Shift 1)

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