The $O_2$ dissociation curve is a....

Carbon dioxide is transported via blood to the lungs primarily in which form?

$A$: $100 \; ml$ of venous blood contains $14.4 \; ml$ of $O_2$,meaning it is still $75\%$ saturated with oxygen under normal conditions.
$R$: About $4.6 \; ml$ of $O_2$,i.e.,$25\%$,diffuses from arterial blood into the tissues during resting conditions.

What happens during the toxic effect of carbon monoxide $(CO)$?

Given below are two statements.
Statement $I$: Carbonic anhydrase enzyme is found in $RBCs$ and is absent in plasma.
Statement $II$: The rate of formation of carbonic acid is very high inside $RBCs$ than in plasma.
In light of the above statements, select the correct answer from the options given below.

The toxic effect of carbon monoxide is due to its higher affinity for hemoglobin compared to oxygen. How many times higher is this affinity (in $\text{times}$)?