Haemoglobin is

Identify the incorrect statement regarding the transport of oxygen:

The following statements refer to the transportation of gases. Read them carefully and choose the correct option containing the incorrect statements.
$(i)$ After leaving the lungs, each litre of blood contains about $20 \ ml$ of oxygen.
$(ii)$ When $PCO_2$ rises, the affinity of haemoglobin for oxygen is increased.
$(iii)$ Each litre of arterial blood contains about $4 \ ml$ of $CO_2$.
$(iv)$ The role of oxygen in the regulation of respiratory rhythm is quite significant.

Approximately $70\%$ of carbon dioxide absorbed by the blood is transported to the lungs:

Which respiratory pigment is responsible for transporting oxygen from the blood to the tissues in vertebrates?

Reduction in $pH$ of blood will