Question

which definition best describes a base?

a. a substance in a solution that provides color over a narrow range of ph

b. a substance in a solution that releases hydrogen ions and lowers the ph

c. a substance in a solution that captures hydrogen ions and raises the ph

d. a substance in a solution that releases and captures hydrogen ions, keeping the ph the same

Explanation:

• Option A describes an indicator (like litmus), not a base.
• Option B describes an acid (acids release \(H^+\) and lower pH).
• Option C: Bases (e.g., \(OH^-\) - containing compounds or proton acceptors) capture \(H^+\) (e.g., \(OH^- + H^+

ightarrow H_2O\)), which reduces \(H^+\) concentration and raises pH.

• Option D describes a buffer, not a base.

Answer:

C. A substance in a solution that captures hydrogen ions and raises the pH