Question

The half life of a first order reaction is 30 min and the initial concentration of the reactant is 0.1 M. If the initial concentration of reaction of reactant is doubled, then the half life of the reaction will be
(a) 1800 s
(b) 60 min
(c) 10 min
(d) 900 s

Answer 1

Answer:

option a.

Explanation:

for 1st order reaction half life is independent of initial concentration.

Answer 2

Answer:

900 s

Explanation:

We have been given

Half life of first order is T₁ = 30 min

T₁ = 30 × 60 = 1800 s

Concentration  of the reactant is  K₁ = 0.1 M

If concentration of reactant is doubled K₂ = .2 M

Now ,

T₁ × K₁ = T₂ × K₂

1800 × 0.1 = T ₂ × 0.2

Half life of reaction will be  900 s