In mammals,how much $CO_2$ is transported as bicarbonates of sodium and potassium in the blood?

In blood,the majority of $CO_2$ is transported by which of the following?

Select the incorrect statement regarding hemoglobin.

With reference to the oxyhaemoglobin dissociation curve,select the $INCORRECT$ statement/statements.
$I$. $100\%$ saturation is very common.
$II$. $95-97\%$ saturation takes place at $ppO_2 = 100 \text{ mm Hg}$ in alveoli.
$III$. At $30 \text{ mm Hg}$ of $ppO_2$,only $50\%$ saturation can be maintained.
$IV$. The oxyhaemoglobin dissociation curve is $J$-shaped.
Select the correct option.

The toxic effect of carbon monoxide is due to its higher affinity for hemoglobin compared to oxygen. How many times higher is this affinity (in $\text{times}$)?

What percentage of $O_2$ is transported by hemoglobin (in $\%$)?