Question

A first-order reaction has a half-life of
15 minutes. What fraction of the initial
concentration will be left after
90 minutes?
2 Marks​

Answer 1

Nice question mate !!!

The concentration left after certain time

$A = (\frac{Ao}{2}) ^{n}$

where n = t/(T)1/2

n = 90/15 = 6

Therefore

       $A = (\frac{Ao}{64}) }$

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