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

Identify the correct sentence.

Identify the incorrect statement regarding the transport of oxygen:

Haemoglobin has maximum affinity with

At which level does the following reaction occur?
$H^+ + HCO_3^- \rightarrow H_2CO_3 \rightarrow H_2O + CO_2$

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.