The mechanism for the reaction is given below:
$2P + Q \to S + T$
$P + Q \to R + S$ (slow)
$P + R \to T$ (fast)
The rate law expression for the reaction is:

Assertion: The order of a reaction can have a fractional value.
Reason: The order of a reaction cannot be determined from the balanced chemical equation of a reaction.

Rate of reaction for $2X + Y \rightarrow 3W + Z$ is $1.2 \times 10^{-4} \ mol \ dm^{-3} \ sec^{-1}$ when $[X] = [Y] = 0.6 \ mol \ dm^{-3}$. Calculate the value of the rate constant if the reaction is first order in $X$ and zero order in $Y$.

Which one of the following statements is wrong?

Which of the following statements regarding the order of a reaction is incorrect?

The reaction $2X + Y \to X_2Y$ follows the mechanism given below:
$2X \rightleftharpoons X_2$ (Fast)
$X_2 + Y \to X_2Y$ (Slow)
Determine the order of the reaction.