What is meant by the rate controlling step in a reaction?

Consider the following reaction

$\mathrm{A} \underset{{\mathrm{k}}_{-1}}{\overset{{\mathrm{k}}_1}{\rightleftharpoons }} \mathrm{M}+\mathrm{C} ; \mathrm{M}+\mathrm{B} \stackrel{{\mathrm{k}}_2}{\to } \mathrm{Products} (\mathrm{Slow} \mathrm{step})$

The rate can be expressed as

Consider the given plots for a reaction obeying Arrhenius equation $(0°C<T<300°C):$ ($K$and $E_a$ are rate constant and activation energy, respectively )

(I) 

(II) 

The reaction $2\mathrm{NO}+{\mathrm{Br}}_2\to 2\mathrm{NOBr}$ takes place through the mechanism given below

$\mathrm{NO}+{\mathrm{Br}}_2\stackrel{}{\rightleftharpoons }{\mathrm{NOBr}}_2 \left(\mathrm{fast}\right)$

${\mathrm{NOBr}}_2+\mathrm{NO}\to 2\mathrm{NOBr} \left(\mathrm{slow}\right)$

The overall order of the reaction is _____.

For a reaction $2{\mathrm{H}}_2{\mathrm{O}}_2$

$2{\mathrm{H}}_2{\mathrm{O}}_2\underset{\mathrm{Alkaline} \mathrm{medium}}{\overset{{\mathrm{I}}^{-}}{\to }}2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$

The proposed mechanism is as given below:

1. ${\mathrm{H}}_2{\mathrm{O}}_2+{\mathrm{I}}^{-}\to {\mathrm{H}}_2\mathrm{O}+{\mathrm{IO}}^{-}$ (slow)

2. ${\mathrm{H}}_2{\mathrm{O}}_2+{\mathrm{IO}}^{-}\to {\mathrm{H}}_2\mathrm{O}+{\mathrm{I}}^{-}+{\mathrm{O}}_2$ (fast)

Out of steps (1) and (2), which one is rate-determining step?

For a reaction, $\mathrm{X}+\mathrm{Y}\to \mathrm{product}$

The rate law, is Rate, $\mathrm{K}={\left[\mathrm{X}\right]}^{\frac{1}{2}}\left[\mathrm{Y}\right]$. Can this reaction be an elementary reaction?

The reaction rate for the reaction

${\left[{\mathrm{PtCl}}_4\right]}^{2-}+{\mathrm{H}}_2\mathrm{O}\rightleftharpoons {\left[\mathrm{Pt}\left({\mathrm{H}}_2\mathrm{O}\right){\mathrm{Cl}}_3\right]}^{-}+{\mathrm{Cl}}^{-}$

was measured as a function of concentrations of different species. It was observed that

$\frac{-\mathrm{d}\left[{\left[{\mathrm{PtCl}}_4\right]}^{2-}\right]}{\mathrm{dt}}=4.8\times {10}^{-5}\left[{\left[{\mathrm{PtCl}}_4\right]}^{2-}\right]-2.4\times {10}^{-3}\left[{\left[\mathrm{Pt}\left({\mathrm{H}}_2\mathrm{O}\right){\mathrm{Cl}}_3\right]}^{-}\right]\left[{\mathrm{Cl}}^{-}\right]$

where square brackets are used to denote molar concentrations. The equilibrium constant

${\mathrm{K}}_{\mathrm{c}}=X$(Nearest integer)

Value of $\frac{1}{X} is$ (question is modified.)

For an elementary chemical reaction, ${\mathrm{A}}_2 \underset{{\mathrm{k}}_{-1}}{\overset{{\mathrm{k}}_1}{\rightleftarrows }}2\mathrm{A}$ , the expression for $\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$ is:

For a reaction, consider the plot of $lnk$ versus $1/T$ given in the figure. If the rate constant of this reaction at $400K$ is ${10}^{-5}{s}^{-1}$ , then the rate constant at $500K$ is:

For a reaction rate law expression is :

Rate = $\mathrm{K}{\left[\mathrm{A}\right]}^{\frac{1}{2}}{\left[\mathrm{B}\right]}^2$.

Can the reaction be an elementary ? Explain. 

The reaction $2 \mathrm{A}+{\mathrm{B}}_2\to 2\mathrm{AB}$ is an elementary reaction.

For a certain quantity of reactants, if the volume of the reaction vessel is reduced by a factor of $3,$ the rate of the reaction increases by a factor of _____ . (Round off to the Nearest Integer).