In a reaction if the concentration of reactant A is tripled the rate of the reaction is becomes 27 times. What is the order of the react?

Method 1 :

Assume that the order of reaction is n.
Then, R = k [A]ⁿ

Originally, when [A] = [A]ₒ, R = Rₒ :
Rₒ = k ([A]ₒ)ⁿ …… (i)

When [A] = 3[A]ₒ, R = 27Rₒ :
27Rₒ = k (3[A]ₒ)ⁿ …… (ii)

(ii)/(i) :
27 = 3ⁿ
3ⁿ = 3³
n = 3

The order of reaction = 3


====
Method 2 :

When the concentration of A is tripled (3 times) :
The reaction rate = 27 times = 3³ times

Therefore, the order of reaction = 3

3