The red colour of oxyhaemoglobin is mainly due to

Step-by-step solution

When oxygen is bound to F e 2 + in heme, all the d-electrons of the Fe atom are forced into the three lower energy t 2 g orbitals and it produces low spin oxyhaemoglobin. In oxyhaemoglobin, F e 2 + = A r 3 d 6 The sharp high energy transition between t 2 g and e g levels of the d-electrons is responsible for the bright red colour of oxyhaemoglobin.