b
\((i) \quad N O(g)+B r_{2}\,(g) \rightleftharpoons N O B r_{2}\,(g)\)

\((ii) \quad \operatorname{NOBr}_{2}(g)+N O(g) \longrightarrow 2 N O B r\,(g)\)

Rate law equation \(=k\left[N O B r_{2}\right][N O]\)

But \(N O B r_{2}\) is intermediate and

must not appear in the rate law equation

from \(1^{st}\) step \(K_{C}=\frac{\left[N O B r_{2}\right]}{[N O]\left[B r_{2}\right]}\)

\(\therefore \quad\left[N O B r_{2}\right]=K_{C}[N O]\left[B r_{2}\right]\)

Rate law equation \(=k . K_{C}[N O]^{2}\left[B r_{2}\right]\)

hence order of reaction is \(2\) wr.t. \(N O .\)