A `0.10 M` aqueous solution of which salt in each of the following pairs would have the higher `pH`?
a. `NanO_(2)` or `NaAsO_(2)`
b. `NaF` or `NaCN`
c. `Na_(2)SO_(3)` or `Na_(2)TeO_(3)`
d. `NaOHCl` or `NaOBr`

Explanation

The stronger the acid, the weaker is its conjugate base. The oxyacids are stronger towards the top of the periodic table
`HNO_(2)` is a stronger acid, hence, `NO_(2)^(ɵ)` is a weaker base. Therefore, `AsO_(2)^(ɵ)` has a higger `pH`( Note: Higher `pH` means more basic, and lower `pH` means more acidic.)
b. `HF` is a stronger acid, hence, `F^(ɵ)` is a weaker base. Therefore, `CN^(ɵ)` has a higher `pH`.
c. `H_(2)SO_(3)` is a stronger acid , `SO_(3)^(2-)` is a weaker base, `TeO_(3)^(2-)` has a higher `pH`.
d. `HOCl` is a stonger acid, `OCl^(ɵ)` is a weaker base, `OBr^(ɵ)` has a higher `pH`.