Differential form of the rate equation is

$\frac{{dx}}{{dt}} = k\left[ P \right]{\left[ Q \right]^{0.5}}{\left[ R \right]^{0.5}}$ 

Which statement about the above equation is wrong?

What is the molecularity of the following reaction ?

$1.$ $NH _{4} NO _{2( s )} \rightarrow N _{2( g )}+2 H _{2} O$

$2.$ $2 HI \rightarrow H _{2}+ I _{2}$

$3.$ $2 NO + O _{2} \rightarrow 2 NO _{2}$

In hydrogenation reaction at ${27\,^o}C$, it is observed that hydrogen gas pressure falls from $2\,atm$ to $1.2\,atm$ in $50\,\min$. Calculate the rate of disappearance of hydrogen

The order of a reaction is said to be $ 2 $ with respect to a reactant $X, $ when

For a reaction $A \to B$, the rate of reaction quadrupled when the concentration of $A$  is doubled. The rate expression of the reaction is $r = K{(A)^n}$. when the value of $n$ is

Reaction : $KCl{O_3} + 6FeS{O_4} + 3{H_2}S{O_4} \to $ $KCl + 3F{e_2}{\left( {S{O_4}} \right)_3} + 3{H_2}O$

Which is True $(T)$ and False $(F)$ in the following sentence ?

The reaction is elementary.