Under which condition,dissociation of oxygen from oxyhaemoglobin in tissues occurs?

At which level does the following reaction occur?
$H^+ + HCO_3^- \rightarrow H_2CO_3 \rightarrow H_2O + CO_2$

During oxygen transport,the oxyhaemoglobin at the tissue level liberates oxygen to the cells because

Exposure to carbon monoxide (from coal gas) is extremely dangerous and can kill a patient because

Every $100 \ ml$ of oxygenated blood can deliver around $............$ of $O_2$ to the tissues under normal physiological conditions. (in $ml$)

Carbon monoxide combines with haemoglobin to form . . . . . . .