8) Rank the following protons (lubelco HD) in order of decreasing acidity Explain using ARIO

HA$\Rightarrow$H⁺+A^-

The acidity of a molecule (HA) depends on the stability of the conjugate base (A^-).

This can be determined via ARIO rule

The stability of the -ve charge on the conjugate base depends on the following four factors.
1. The type of atom that carries the charge (A): Size and electronegativity of the -ve charge-carrying atom. Greater the size of the atom, the more stable the -ve charge. Similarly greater the electronegativity of the atom, the more stable the conjugate base. 
2. Resonance (R): Resonance stabilizes the -ve charge by delocalization. Hence greater the chance for such resonance, the more stable the conjugate base. 
3. Induction (I): Induction can also stabilize the -ve charge on the conjugate base by spreading it out.
4.  The type of orbital where the charge resides (O): Shorter the size of the atomic orbital where the electron pair is residing, the greater its stability.

These factors construct the acronym, ARIO. While comparing the acidity of protons, we generally use ARIO as
the order of importance of these stabilizing effects.