Arrange the following acids in the correct increasing order of their acidic strength,
HCl, HBr, HI, HF

Explanation

As the size of the atom (X) increases from F to I, the bond length of the H-X bond increases and consequently bond dissociation enthalpy of the H-X bond decreases. In other bonds, bond dissociation enthalpy increases in the ordr : `HI lt HBr lt HCl lt HF`