To solve this problem, we need to analyze each statement regarding the transport of oxygen and identify the incorrect one. Let's evaluate each option:$\newline \bullet$Option 1: Partial pressure of CO$_2$ can interfere with O$_2$ binding with haemoglobin.$\newline$ - This statement is correct. The presence of CO$_2$ affects the affinity of haemoglobin for oxygen, a phenomenon known as the Bohr effect.$\newline \bullet$Option 2: Higher H$^+$ concentration in alveoli favours the formation of oxyhaemoglobin.$\newline$ - This statement is incorrect. Higher H$^+$ concentration (lower pH) actually reduces the affinity of haemoglobin for oxygen, promoting oxygen release rather than binding.$\newline \bullet$Option 3: Low pCO$_2$ in alveoli favours the formation of oxyhaemoglobin.$\newline$ - This statement is correct. Low partial pressure of CO$_2$ in the alveoli increases the affinity of haemoglobin for oxygen, facilitating the formation of oxyhaemoglobin.$\newline \bullet$Option 4: Binding of oxygen with haemoglobin is mainly related to partial pressure of O$_2. \newline$ - This statement is correct. The primary factor affecting oxygen binding to haemoglobin is the partial pressure of oxygen (pO$_2$).$\newline$Therefore, the incorrect statement is Option 2, which states that higher H$^+$ concentration in alveoli favours the formation of oxyhaemoglobin.$\newline$Thus, the correct answer is Option 2.