Different substrates get oxidized during respiration. How does Respiratory Quotient $(RQ)$ indicate which type of substrate,i.e.,carbohydrate,fat or protein is getting oxidized?

(A) The Respiratory Quotient $(RQ)$ is defined as the ratio of the volume of $CO_2$ evolved to the volume of $O_2$ consumed during respiration.
$RQ = \frac{\text{Volume of } CO_2 \text{ evolved}}{\text{Volume of } O_2 \text{ consumed}}$
$RQ$ values help identify the respiratory substrate:
$1$. For carbohydrates,the $RQ$ is $1$ because the volume of $CO_2$ evolved equals the volume of $O_2$ consumed.
$2$. For fats and proteins,the $RQ$ is less than $1$ $(< 1)$ because they require more oxygen for oxidation relative to the $CO_2$ produced.
$3$. For organic acids,the $RQ$ is greater than $1$ $(> 1)$ because they are already oxygen-rich and produce more $CO_2$ relative to the $O_2$ consumed.