Question

The dissociation constants of monobasic acids A,B,C and D are $6\times {10}^4,5\times {10}^5,3.6\times {10}^{6}and7\times {10}^{10}$ respectively. The pH values of their 0.1 molar aqueous solutions are in the order:

• A. A < B < C < D
• B. A > B > C > D
• C. A = B = C = D
• D. A > B < C > D

Answer 1

The correct option is B A > B > C > D

As the dissociation constant increases (A<B<C<D), dissociation of acid increases (A<B<C<D) and hence $\left[H^{+}\right]$ increases (A<B<C<D) and hence pH value decreases (A>B>C>D).