Which of the following option contain wrong statement regarding exchange of gases?

(i) Alveoli are the primary sites of exchange of gases.

(ii) Exchange of gases also occurs between blood and tissues.

(iii) O 2 and CO 2 are exchanged mainly based on pressure/concentration gradient.

(iv) Solubility of the gases as well as the thickness of the membranes involved in diffusion are also some important factors that can affect the rate of diffusion.

(v) Solubility of CO 2 is 20-25 times lower than that of O 2 .

(vi) The amount of CO 2 that can diffuse through the diffusion membrane per unit difference in partial pressure is much lower compared to that of O 2 .