Predict which compound in each of the following pairs of compounds is more acidic and explain your reasoning for each.

1. \(HSO_4^ - or\; HSeO_4^ - \)
2. \(N{H_3}\;or\;{H_2}O\)
3. \(P{H_3}\;or HI\)
4. \(N{H_3}\;or\;P{H_3}\)
5. \({H_2}S\;or\;HBr\)

The stronger acid releases the hydrogen ions in the water solution more easily than the weaker ones.

Here,\({\rm{HSO}}_4^ - \)is more acidic of the two as it is a weaker basecompared to the conjugated acids \({{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\) and \({{\rm{H}}_2}{\rm{Se}}{{\rm{O}}_4}\).

The hydrogen atom from \({\rm{HSO}}_4^ - \) releases more easily to form sulphate ion \({\rm{SO}}_4^{2 - }\) than from \({\rm{HSeO}}_4^ - \).

As \({{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\) is the strong acid and its conjugated pair is a weak base (\({\rm{HSO}}_4^ - \)).

Here, \({{\rm{H}}_2}{\rm{O}}\) is more acidic of the two because \({\rm{N}}{{\rm{H}}_{\rm{3}}}\) is a base.

Acid releases proton and bases extract proton to form the aqueous solution.

Ammonia \({\rm{N}}{{\rm{H}}_{\rm{3}}}\) is a base.

Here, \(HI\) is more acidic of the two because \(HI\) is moderately strong acid.

In the periodic table for \(P\)is below \(N\).

Ammonia \({\rm{N}}{{\rm{H}}_{\rm{3}}}\) is a base but \({\rm{P}}{{\rm{H}}_{\rm{3}}}\) is not a base nor an acid.

HI can release proton more easily.

Here, \({\rm{P}}{{\rm{H}}_{\rm{3}}}\) is more acidic of the two \(N\) and \(P\) are present in the same column.

As per the periodic table, the acid strength increases and the base strength decreases from the top to the bottom of the column.

Ammonia \({\rm{N}}{{\rm{H}}_{\rm{3}}}\) is a base but \({\rm{P}}{{\rm{H}}_{\rm{3}}}\) is not a base nor an acid.

\(HBr\)shows some similar properties to HCl and bromine is present below chlorine in periodic table.

\({{\rm{H}}_2}{\rm{O}}\)is neutral and \({{\rm{H}}_2}{\rm{S}}\) is present below oxygen.

Therefore, HBr can releases proton more easily than \({{\rm{H}}_2}{\rm{S}}\).