During oxygen transport,the oxyhaemoglobin at the tissue level liberates oxygen to the cells because in tissue:

The exchange of gases in the alveoli of the lungs takes place by

Name the primary site of exchange of gases in our body?

$A$: Diffusion of carbon dioxide is $20$ times faster than oxygen.
$R$: It is due to difference in partial pressure as well as solubility of diffusing gases.

Given below are two statements.
Statement $I$: Respiratory membrane is composed of two layers of squamous epithelia,each resting on a thick basement membrane.
Statement $II$: The diffusion of a respiratory gas takes place from lower partial pressure to higher partial pressure of the same.
In the light of above statements,choose the most appropriate answer from the options given below:

Match the partial pressures of oxygen in different parts involved in diffusion compared to the atmosphere.

Column-$I$	Column-$II$ ($PO_2$ in $mm\, Hg$)
$P$. Atmospheric air	$I$. $159$
$Q$. Tissues	$II$. $95$
$R$. Oxygenated blood	$III$. $40$