At what concentration of the reactant (in $M$) are the rate constants for first-order,second-order,and third-order reactions equal?

The rate of the reaction: $2N_2O_5 \rightarrow 4NO_2 + O_2$ can be written in three ways.
$-\frac{d[N_2O_5]}{dt} = k[N_2O_5]$
$\frac{d[NO_2]}{dt} = k'[N_2O_5]$ ; $\frac{d[O_2]}{dt} = k''[N_2O_5]$
The relationship between $k$ and $k'$ and between $k$ and $k''$ are:

The three experimental data for determining the differential rate of reaction $2 NO_{(g)} + Cl_{2(g)} \rightarrow 2 NOCl_{(g)}$ at a definite temperature are given below.
$(a)$ Calculate the order of reaction.
$(b)$ Calculate the value of the rate constant.

Assertion : The kinetics of the reaction $mA + nB + pC \to m'X + n'Y + p'Z$ obey the rate expression as $\frac{dX}{dt} = k[A]^m[B]^n$.
Reason : The rate of the reaction does not depend upon the concentration of $C$.

$(a)$ Write the general reaction and derive the units of the rate constant. $(b)$ Based on that,write the rate constant units for zero,first,and $2^{nd}$ order reactions.

The reaction rate between two substances $A$ and $B$ is expressed as: $\text{rate} = k[A]^n[B]^m$. If the concentration of $A$ is doubled and the concentration of $B$ is halved,the ratio of the new rate to the initial rate will be: