Question

The majority of CO${}_2$ is transported into blood as

• A. Bicarbonate
• B. Sulphate
• C. Oxalate
• D. Citrate

Answer 1

The correct option is A Bicarbonate

Carbon dioxide produced in the tissue cells diffuses into the blood plasma. The largest fraction of carbon dioxide diffuses into the blood cells as bicarbonate. The formation of bicarbonate ions (HCO${}_3$-) takes place by the following reactions:
Hydration of CO${}_2$: CO${}_2$ + HOH --> H${}_2$CO${}_3$
Dissociation of H${}_2$CO${}_3$: H${}_2$CO${}_3$ --> H+ + HCO${}_3$-
Thus, the correct answer is option A.