Whales are air-breathers but can live underwater for a long time because they possess:

During rest,the metabolic needs of the body are at their minimum. Which of the following is indicative of this situation?

$I.$ $pO_2$ is the major factor which affects the binding of $CO_2$ with haemoglobin.
$II.$ $pCO_2$ is low and $pO_2$ is high in tissues.
$III.$ $RBC$ contains a very high concentration of carbonic anhydrase.
$IV.$ Every $100 \; mL$ of deoxygenated blood delivers approximately $4 \; mL$ of $CO_2$ to alveoli.
Select the combination of right statements.

What is the approximate amount of $CO_2$ eliminated by our lungs per day?

Match the following columns and select the correct option:

Column $I$	Column $II$
$(a)$ Pneumotaxic Centre	$(i)$ Alveoli
$(b)$ $O_{2}$ Dissociation curve	$(ii)$ Pons region of brain
$(c)$ Carbonic Anhydrase	$(iii)$ Haemoglobin
$(d)$ Primary site of exchange of gases	$(iv)$ $R.B.C.$

Which of the following is a respiratory gas?