Gas phase reactions (i) and (ii) are of first and second order respectively, where
(i) is $$2\text{N}_2\text{O}_5 \rightarrow 4\text{NO}_2 + \text{O}_2$$ and
(ii) is $$2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2$$.
Under certain conditions the rate constants $$k_1$$ and $$k_2$$ of (i) and (ii) respectively have the same numerical value when the concentrations of the reactants are expressed in mol $$\text{dm}^{-3}$$. If the concentrations are expressed in mol $$\text{mL}^{-1}$$, the correct relationship between $$k_1$$ and $$k_2$$ is