Carbon dioxide is transported in the bloodstream chiefly in the form of?

dissolved form, carbonic acid

Explanation:

Carbon dioxide is transported by the blood in the dissolved form. carbonic anhydrase is the enzyme which is a metalloenzyme having zinc at active site converts carbon dioxide into carbonic acid which dissolves in the blood and is reached at the lungs where the acid is again converted to carbon dioxide to exhale out.

Thus,

(a) carbonic acid.

H₂O (l) + CO₂ (g) ⇔ H₂CO₃ (aq)

(b) bicarbonate ion. (Acts as a buffer in the blood)

H₂CO₃ (aq) ⇔ H⁺ (aq) + HCO₃²⁻ (aq)