Oxygen is transported by

Although a large amount of $CO_2$ is transported in the blood,the blood does not become acidic because:

What happens when the blood becomes acidic?

What conditions in the alveoli favor the dissociation of carbon dioxide from carbaminohemoglobin?

Which factors in the tissues favor the dissociation of oxygen from oxyhaemoglobin?

Select the correct option:
$(1)$ Approximately $97\%$ of $O_2$ is transported by plasma / RBCs.
$(2)$ The primary site of gas exchange is alveoli / bronchioles.