(i) The magnitude of order of a reaction may be zero, or fractional or integral values. For an elementary reaction, its order is never fractional since it is a one step process.
(ii) Order of a reaction should be determined only by experiments. It cannot be predicted in terms of stoichiometry of reactants and products.
(iii) Simple reactions possess low values of order line n=0,1,2. Reactions with order greater than or equal to 3.0 are called complex reactions. Higher order reactions are rare.
(iv) Some reactions show fractional order depending on rate.
(v) Higher order reactions may be experimentally converted into simpler order (Pseudo) reactions by using excess concentrations of one or more reactants.