The solubility of $CO_2$ is ....... times higher than that of $O_2$.

Arrange the appropriate pair.

Column-$I$	Column-$II$ (Amount of $CO_2$ in $mm \ Hg$)
$(a)$ Alveoli	$(1)$ $40$
$(b)$ Tissue	$(2)$ $45$
$(c)$ Blood without $O_2$ (Deoxygenated)	$(3)$ $40$
$(d)$ Blood with $O_2$ (Oxygenated)	$(4)$ $45$

What is the partial pressure of oxygen $(pO_2)$ in the alveoli of the lungs compared to the blood?

Through which process is oxygen transported from the lungs to the tissues?

The figure given below shows a small part of human lung where exchange of gases takes place. Select the option which represents labelled part ($A, B, C$ or $D$) correctly identified along with its function.

The partial pressure of $O_{2}$ and $CO_{2}$ in atmospheric air as compared to those in alveolar air is:

Gas	Alveolar Air $(X/A)$	Atmospheric Air $(Y/B)$
$pO_{2}$	$X$	$Y$
$pCO_{2}$	$A$	$B$