Question

Why Oxyhaemoglobin is an unstable compound?

Answer 1

It is simply not bound very tightly. The binding of oxygen to hemoglobin is a reversible reaction that is based on the partial pressure of oxygen; it is also a function of the pH of the environment (oxygen is held less tightly in lower pHs)

Answer 2

Bcoz there is a chemical bonding between oxygen and hemoglobin.