Why does the blood not become acidic during the transport of $CO_2$?

What is the shape of the oxygen-hemoglobin dissociation curve?

Which enzyme is present in $RBC$s and plasma to catalyse the given reaction: $CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$?

The majority of carbon dioxide produced by our body cells is transported to the lungs as

Carbonic anhydrase is found in

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.