If the rate constant of a reaction is k = 3 × 10^-4 s^-1, then what is the order of the reaction?

First order

Unit of rate constant = (mole)^1-n (litre)^n-1 time^-1    ......... (i)

where n = order of reaction

Given: k = 3 × 10^-4 s^-1 

it also can be written as k = 3 × 10^-4 (mole)⁰ (litre)⁰ s^-1   ..........(ii)

comparing exponents from equation (i) and (ii), we get

1-n = 0

n = 1