Which of the following statements is/are true for a 0.10 m solution of a strong acid (HA) ?

The question is incomplete; the complete question is;

Which of the following statements is/are true for a 0.10 M solution of a weak acid HA?

a. [ H+] >> [ A-]

b. [ H+] = [ A-]

c. The pH is 1.00.

d. The pH is less than 1.00.

Answer:

b. [ H+] = [ A-]

Explanation:

Given the acid as HA, we know that being a weak acid, its dissociation in water can never be 100%. If it were a strong acid, then it could have undergone a 100% dissociation in solution. The conjugate base of a weak acid is a always a weak base hence A^ - is expected to act as a weak base. At the same concentration, weak acids have a higher pH value than strong acids. Hence if the pH of a strong acid HA is 1, then the pH of a weak acid HA must be greater than 1.

But, we look at the equation for the dissociation of the weak acid HA

HA (aq) ⇄H^ - (aq) + A^ - (aq). This implies that the HA dissociates in a 1:1 ratio therefore; [H+] = [ A-], hence the answer given above.