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

Blood leaving the lungs is rich in:

Which of the following is correct regarding the partial pressures of gases ($PO_2$ and $PCO_2$) in different parts of the human respiratory system?

Which of the following is true regarding $CO_2$ concentration?

The diagram below represents part of a capillary in a specific region of the human body. The region labeled $X$ represents part of

How much $CO_2$ is delivered to the alveoli by every $100 \;ml$ of deoxygenated blood (in $;ml$)?