If the rate of the reaction is equal to the rate constant, the order of the reaction is

For the reaction, 

$2\mathrm{A} +\mathrm{B}\stackrel{}{\to }3\mathrm{C} + \mathrm{D},$

which of the following does NOT express the reaction rate?

Consider the reaction ${\mathrm{N}}_{2\left(\mathrm{g}\right)}+3{\mathrm{H}}_{2\left(\mathrm{g}\right)}\to 2{\mathrm{NH}}_{3\left(\mathrm{g}\right)}$.

The equality relationship between $\frac{\mathrm{d}\left[{\mathrm{NH}}_3\right]}{\mathrm{dt}}$ and$\frac{\mathrm{d}\left[{\mathrm{H}}_2\right]}{\mathrm{dt}}$ is:

For the reaction $\mathrm{A}+\mathrm{B}⟶$ products, it is observed that: 

(1) On doubling the initial concentration of $\mathrm{A}$ only, the rate of reaction is also doubled and
(2) On doubling the initial concentrations of both $\mathrm{A}$ and $\mathrm{B}$, there is a change by a factor of $8$ in the rate of the reaction.

The rate of this reaction is given by: