2.2 liters at 20 degrees celsius if the pressure doesn’t change what is the new temperature at 2.6 liters

Based on the question, it is evident that this question rests on the premise of Charle's Law, which essentially states that temperature is proportional to volume once pressure and mass remain constant.

Thus by Charle's Equation:   

Since the initial volume = 2.2 L; the initial temperature = 20 C; and the final volume = 2.6 L,
                           then V₁ = 2.2 L; T₁ = 20 C; V₂ = 2.6 L and what we would be
                           finding is T₂ (the final/new temperature)

Now,    

     ⇒   

     ⇒   

        ∴  the new temperature is ≈  23.6 °C

They carry out the exchange of gases as we breathe ( oxygen and carbon dioxide).