$A$ complex reaction takes place in $2$ steps:
$(I)$ $NO_{2(g)} + F_{2(g)} \rightarrow NO_2F_{(g)} + F_{(g)}$ (slow)
$(II)$ $F_{(g)} + NO_{2(g)} \rightarrow NO_2F_{(g)}$ (fast)
Identify the reaction intermediate.

For the reaction $A + B \to \text{products}$,it is found that the rate of the reaction is proportional to the concentration of $A$,but it is independent of the concentration of $B$. Then:

For the reaction $Cl_{2(aq)} + H_2S_{(aq)} \to S_{(s)} + 2H^+_{(aq)} + 2Cl^-_{(aq)}$, the rate law is given by $\text{Rate} = K[Cl_2][H_2S]$. Which of the following mechanisms is consistent with this rate law?
$(A)$ $Cl_2 + H_2S \to H^+ + Cl^- + Cl^+ + HS^-$ (slow); $Cl^+ + HS^- \to H^+ + Cl^- + S$ (fast)
$(B)$ $H_2S \rightleftharpoons H^+ + HS^-$ (fast equilibrium); $Cl_2 + HS^- \to 2Cl^- + H^+ + S$ (slow)

The rate law for the reaction $A + B \rightarrow \text{product}$ is given by $\text{rate} = k[A][B]$. Calculate $[A]$ if the rate of reaction and rate constant are $0.25 \ mol \ dm^{-3} \ s^{-1}$ and $6.25 \ mol^{-1} \ dm^3 \ s^{-1}$ respectively,and $[B] = 0.25 \ mol \ dm^{-3}$.

In the reaction,$P + Q \longrightarrow R + S$,the time taken for $75 \%$ reaction of $P$ is twice the time taken for $50 \%$ reaction of $P$. The concentration of $Q$ varies with reaction time as shown in the figure. The overall order of the reaction is

The time required for a definite fraction of a reaction to complete is inversely proportional to the initial concentration of the reactant. Find the order of the reaction.