$A$ large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This $O_{2}$

The dissociation curve is associated with

To which part of $Hb$,$CO_2$ binds?

When temperature decreases,the oxyhaemoglobin dissociation curve will become:

Given below are two statements:
Statement $I$: The relationship between $HbO_2$ saturation and oxygen tension $(pO_2)$ is called the oxygen-dissociation curve.
Statement $II$: The oxygen dissociation curve shifts towards the right due to a decrease in $ppCO_2$ and a decrease in temperature.
In the light of the above statements,choose the most appropriate answer from the options given below.

$CO_2$ is primarily transported in the blood in the form of: