Q.Mark the incorrect statement in context to O2 binding to Hb

Working through the four options against the conditions that favour oxygen binding to haemoglobin (which occur in the alveoli): a higher pH (that is, a lower hydrogen-ion/acidity level) favours binding, a lower temperature favours binding, a lower carbon-dioxide pressure favours binding, and a higher oxygen pressure favours binding. All four of these, as stated, actually describe conditions that favour — rather than oppose — oxygen binding to haemoglobin, so none of them stands out as a clearly incorrect statement based on this chapter's own account of the factors involved. …

Whether oxygen binds to haemoglobin depends chiefly on the partial pressure of oxygen, with the partial pressure of carbon dioxide, the hydrogen-ion (acidity) concentration, and the temperature acting as additional influencing factors. The conditions in the alveoli — high oxygen pressure, low carbon-dioxide pressure, low hydrogen-ion concentration (equivalent to a higher pH), and comparatively lower temperature — are explicitly described as favouring the formation of oxyhaemoglobin, that is, favouring O2 binding.

Checking each option against this account: higher pH corresponds to lower hydrogen-ion concentration, which favours binding; lower temperature matches the alveolar condition that favours binding; lower carbon-dioxide pressure matches the alveolar condition that favours binding; and higher oxygen pressure is the primary driver of binding itself. All four, therefore, describe conditions consistent with — not contrary to — oxygen binding. …

Method: Checking a List of Conditions Against the Known Binding-Favouring Factors

Use this approach for any question that lists several physiological conditions and asks which one does NOT favour O2 binding to haemoglobin.

Steps

Step 1: Write down the reference set of binding-favouring conditions

High pO2, low pCO2, low H+ concentration (i.e. higher pH), and lower temperature are the alveolar-type conditions known to favour O2-haemoglobin binding.

Step 2: Restate each listed condition in the same terms

Go through the list and rewrite each option in the reference set's own language (e.g. "higher pH" means the same thing as "lower H+") so every option can be compared directly rather than left ambiguous.

Step 3: Find the mismatch, or flag if there is none …