`pK_(a)` values of three weak acids HA, HB and HC are 4.74, 3.35 and 5.24 respectively. The concentration of aqueous solutions of each of the three acids is 0.01 (M). Arrange them in order of increasing pH values.

Explanation

Since `pK_(a)=-log_(10)K_(a)` , an acid with a smaller value of `K_(a)` will have a larger value of `pK_(a)`. Hence, the order of `K_(a)` values of the given acids is: `K_(a)(HC) lt K_(a)(HA) lt K_a(HB)`.
Again, an acid with a larger ionisation constant will have a higher degree of ionisation and consequently a higher molar concentration of `H_(3)O^(+)` ions in the solution. as a result, the order of concentration of `H_(3)O^(+)` ions in the three solutions will be: `[H_(3)O^(+)]_(HC)lt [H_(3)O^(+)]_(HA) lt [H_(3)O^(+)]_(HB)`. therefore, the increasing order of pH values of the solutions is:
`pH(HB) lt pH(HA) lt pH(HC)`.