Question

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 ?

Answer 1

Answer:

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