pH Scale — Prelims Questions

What is the pH of a 0.001 M solution of NaOH at $25^\circ C$?

A solution has a hydrogen ion concentration of $2.5 \times 10^{-4}$ M. What is its pH?

If the pH of a solution is increased from 3 to 6, what is the change in hydrogen ion concentration?

What is the pH of a solution formed by mixing 50 mL of 0.1 M HCl and 50 mL of 0.05 M NaOH at $25^\circ C$?

Which of the following statements about the pH scale is INCORRECT?

A 0.01 M solution of a weak acid (HA) has a pH of 4.0. What is the acid dissociation constant ($K_a$) for this acid?