Question

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
(a) 0.0075 M (b) 0.06 M
(c) 0.03 M (d) 0.015 M

Answer 1

Answer:

Option B IS THE RIGHT ANSWER.

Hope it helps you

Answer 2

(a) 0.0075 M

Explanation:

Given Half-life is t(1/2) = 4 s

Time T = 16s

n = T/t = 16/ 4 = 4

If A0 is the initial concentration, then concentration left after T is A = A0(1/2)^n = 0.12 * (1/2^4 = 0.12/16 = 0.0075 M

Option A is the answer.