Question

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 : In 2 = 0.693)

Answer 1

$A \ + \ B$
at initially 1 mole 1 mole
after 100 s 1/2 1/4
after 200 s 1/4 1/16

Ans. 200 second