For the chemical reaction, 2 O_3 leftharpoons 3 O_2 The reaction...

As slowest step is the rate determining step. Hence, from slow reaction, $r=K[\mathrm{O}]$\left[\mathrm{O}_3\right]...(i)$From fast reaction,$K_C=\frac{\left[\mathrm{O}_2\right][\mathrm{O}]}{\left[\mathrm{O}_3\right]} $$\begin{aligned} {[\mathrm{O}] } & =\frac{K_C \cdot\left[\mathrm{O}_3\right]}{\left[\mathrm{O}_2\right]}, \text{ i.e. } \\ r & =\frac{K_C\left[\mathrm{O}_3\right]}{\left[\mathrm{O}_2\right]} \cdot\left[\mathrm{O}_3\right]\end{aligned}$$ \Rightarrow K_C \cdot$\left[\mathrm{O}_3\right]^2\left[\mathrm{O}_2\right]^{-1}\therefore$ Rate $(r)=K^{\prime}\left[\mathrm{O}_3\right]^2 \cdot\left[\mathrm{O}_2\right]^{-1}\left(K^{\prime}=K_C \cdot K\right)