A⟶B Initial concentration Rate of reaction 2×10−3M1×10−3M2.40×10−4Ms−10.60×10−4Ms−1 rate of reaction r=k[A]x where x= order of reaction hence 2.40×10−4=k[2×10−3]x0.60×10−4=k[1×10−3]x on dividing eqn.(i) from eqn. (ii) we get 4=(2)x ∴x=2 i.e. order of reaction =2