The rate of a reaction 2X + Y ⟶ Products is given by d[Y] dt = k [X]2 [Y] if X is present in large excess, the order of the reaction is :

Rate of law is; 2 [ ] R k X Y If X is in large excess then rate is independent X. So, this is the case of Pseudo-first order reaction. So, ' R k Y Thus, order = 1