Write two differences between 'order of reaction' and 'molecularity of reaction'.
Order of reaction:
(i) It is the sum of the concentration terms on which the rate of reaction actually depends.
(ii) It can be fractional as well as zero.
Molecularity of reaction:
(i) It is the number of atoms, ions or molecules that must collide with one another simultaneously so as to result into a chemical reaction.
(ii) It is always a whole number.