Molecularity is 2 order is 1.

$$\begin{gathered} \mathrm{A}+\mathrm{B} \to \mathrm{product} \\ \mathrm{r}=\mathrm{k}\stackrel{0}{\left[\mathrm{A}\right]}\left[\mathrm{B}\right] \\ \text{excess of }\mathrm{A}\Rightarrow \text{ order w.r, to }\mathrm{A}=0 \\ \mathrm{overall} \mathrm{order} = 0 + 1 = 1 \\ \mathrm{molecularity} = \mathrm{total} \mathrm{no}. \mathrm{of} \mathrm{species} \mathrm{included} \mathrm{in} \mathrm{the} \mathrm{reaction} \\ \mathrm{A}+\mathrm{B} \to \mathrm{molecularity}=2 \end{gathered}$$