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.

Oxyhemoglobin acts as which of the following?

What are the favorable conditions in the alveoli for the formation of oxyhemoglobin?

Every $100 \ ml$ of deoxygenated blood delivers approximately $.......$ of $CO_2$ to the alveoli $:$ (in $ml$)

What is the amount of oxygen carried by $1 \, g$ of hemoglobin?