You have two beakers. One beaker contains 100 mL of NaOH (a strong base); the other contains 100 mL of aqueous Na3PO4 (a weak base). You test the pH of each solution. Which of the following statements is true?

D. If the pH of NaOH is 12, then that of Na₃PO₄ solution has to be lesser than 12.

Explanation:

In this problem, we are comparing the pH of a strong base to a weak base. A strong base is one that ionizes completely in aqueous solutions where as a weak base ionizes slightly.

The pH scale is good tool for measuring the acidity and alkalinity of various substances. It ranges from 1 - 14;

1 7 14

← →

increasing acidity increasing alkalinity

neutrality

Strong bases have their pH value close to 14 and weak bases are close to 7.

Since Na₃PO₄ is a weak base, it will have lesser pH value compared to a strong base such as NaOH