For the reaction $XA + YB \rightarrow mp + nq$,the rate is given by $\text{Rate} = K[A]^c[B]^d$. What is the overall order of the reaction?

For the reaction $A + B \rightarrow$ products,it is observed that
$(i)$ on doubling the initial concentration of $A$ only,the rate of reaction is also doubled and
$(ii)$ on doubling the initial concentration of both $A$ and $B$,there is a change by a factor of $8$ in the rate of the reaction.
The rate of this reaction is given by

Reaction: $KClO_3 + 6FeSO_4 + 3H_2SO_4 \to KCl + 3Fe_2(SO_4)_3 + 3H_2O$
Which is True $(T)$ and False $(F)$ in the following statement?
The order of this reaction is $2$.

The rate constant of a reaction is $1.388 \times 10^{-3} \ mol^{-2} \ L^{2} \ s^{-1}$. The order of the reaction is:

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 chemical reaction,$A + 2B \to C + D$,the rate of reaction increases $3$ times when the concentration of $A$ only is increased $9$ times. While when the concentration of $B$ only is increased $2$ times,the rate of reaction also increases $2$ times. The order of this reaction is: