$2 \ FeCl_3 + SnCl_2 \rightarrow 2 \ FeCl_2 + SnCl_4$. This reaction is an example of:

Consider the reaction:
$Cl_{2(aq)} + H_2S_{(aq)} \rightarrow S_{(s)} + 2H^{+}_{(aq)} + 2Cl^{-}_{(aq)}$
The rate equation for this reaction is:
$\text{rate} = k[Cl_2][H_2S]$
Which of these mechanisms is/are consistent with this rate equation?
$A.$ $Cl_2 + H_2S \rightarrow H^{+} + Cl^{-} + Cl^{+} + HS^{-}$ (slow)
$Cl^{+} + HS^{-} \rightarrow H^{+} + Cl^{-} + S$ (fast)
$B.$ $H_2S \rightleftharpoons H^{+} + HS^{-}$ (fast equilibrium)
$Cl_2 + HS^{-} \rightarrow 2Cl^{-} + H^{+} + S$ (slow)

For a reaction,$A + 2B \longrightarrow C$,the rate is given by $+\frac{d[C]}{dt} = k[A][B]$. Hence,the order of the reaction is:

Velocity constant $K$ of a reaction is affected by

For a certain chemical reaction $X \rightarrow Y$,the rate of formation of the product is plotted against time as shown in the figure. The number of correct statement$(s)$ from the following is $.......$.
$A$. Overall order of this reaction is one
$B$. Order of this reaction cannot be determined
$C$. In region-$I$ and $III$,the reaction is of first and zero order respectively
$D$. In region-$II$,the reaction is of first order
$E$. In region-$II$,the order of reaction is in the range of $0.1$ to $0.9$.

Why can we not determine the order of a reaction by taking into consideration the balanced chemical equation?