For the following elementary step ${\left({\mathrm{CH}}_3\right)}_3{\mathrm{CBr}}_{\left(\mathrm{aq}\right)}\to \left({\mathrm{CH}}_3\right){\mathrm{C}}_{\left(\mathrm{aq}\right)}^{+}+{\mathrm{Br}}_{(\text{aq) }}^{-}$ the molecularity is:

The term "molecularity" describes how many molecules of reactants are involved in a elementary process.