What should be the nature of blood for the efficient transport of $O_2$ and $CO_2$?

Select the favourable conditions required for the formation of oxyhaemoglobin at the alveoli.

Identify $A$ and $B$ in the given oxygen-haemoglobin dissociation curve and choose the correct option accordingly.

The following statements refer to the transportation of gases. Read them carefully and choose the correct option containing the incorrect statements.
$(i)$ After leaving the lungs, each litre of blood contains about $20 \ ml$ of oxygen.
$(ii)$ When $PCO_2$ rises, the affinity of haemoglobin for oxygen is increased.
$(iii)$ Each litre of arterial blood contains about $4 \ ml$ of $CO_2$.
$(iv)$ The role of oxygen in the regulation of respiratory rhythm is quite significant.

Which of the following major ions in the blood plays an important role in the transport of $CO_2$?

Select the correct option:
$(1)$ Approximately $97\%$ of $O_2$ is transported by plasma / RBCs.
$(2)$ The primary site of gas exchange is alveoli / bronchioles.