For $n$th order of reaction,half-life period is directly proportional to

Why is molecularity applicable only for elementary reactions,while order is applicable for both elementary and complex reactions?

The correct difference between $1^{st}$-order and $2^{nd}$-order reaction is that:

In the reaction $A + B \to \text{Products}$,the initial concentration of both $A$ and $B$ is $0.1 \, M$. When the concentration decreases to $1.0 \times 10^{-2} \, M$,the half-life period increases by ten times. The rate of the reaction is:

In the reaction sequence $A$ $\xrightarrow{K_1} B$ $\xrightarrow{K_2} C$ $\xrightarrow{K_3} D$,where $K_3 > K_2 > K_1$,which step determines the rate of the reaction?

The mechanism of the reaction $A + 2B \to D$ is given by:
$2B \xrightarrow{k} B_2$ [Slow]
$B_2 + A \to D$ [Fast]
The rate law expression,order with respect to $A$,order with respect to $B$,and overall order are respectively: