A reaction takes place in three steps. The rate constant of the three steps are ${\mathrm{K}}_1$ , ${\mathrm{K}}_2$ and ${\mathrm{K}}_3$ respectively. The overall rate constant $\text{K}=\frac{{\text{K}}_1{\text{K}}_3}{{\text{K}}_2}.$
The energy of activation for the three steps are $40$ , $30$ and $20\mathrm{}\mathrm{K}\mathrm{J}$ respectively. Therefore:

The rate expression for the reaction : ${\mathrm{NH}}_4\mathrm{CNO}\rightleftharpoons {\mathrm{NH}}_2{\mathrm{CONH}}_2$ can be derived from the mechanism :

(i) ${\mathrm{NH}}_4\mathrm{CNO}\underset{{\mathrm{K}}_2}{\stackrel{{\mathrm{K}}_1}{\rightleftarrows }}{\mathrm{NH}}_4\mathrm{NCO}$ (Fast)

(ii) ${\mathrm{NH}}_4\mathrm{NCO}\stackrel{{\mathrm{K}}_3}{⟶}{\mathrm{NH}}_3+\mathrm{HNCO}$ (Fast)

(iii) ${\mathrm{NH}}_3+\mathrm{HNCO}\stackrel{{\mathrm{K}}_4}{⟶}{\mathrm{NH}}_2{\mathrm{CONH}}_2$ (Slow)

Which of the following statements are correct about rate expression?