Question

When phenolphthalein is added to $\mathrm{NaOH}$, the colour of the solution will become $\mathrm{\_\_\_\_\_\_\_\_\_\_\_\_}$

• A. Colourless
• B. red
• C. pink
• D. yellow

Answer 1

The correct option is C

pink

Explanation for Correct option:

(c ) Pink

• Because $\mathrm{NaOH}$ is a base, it will turn solution to dark pink, almost purple.
• If you add the appropriate amount of ${\mathrm{H}}_2{\mathrm{SO}}_4$, an acid, it will turn pale pink.
• It is neutral in this circumstance. If you add too much acid, it turns white, indicating that it is acidic.
• so this option is correct.

Explanation for incorrect options :

(a) Colourless

• Because $\mathrm{NaOH}$ is a base, it will turn the solution to dark pink, almost purple
• So it is not colorless.
• Hence this option is not correct.

(b) Red

• Because $\mathrm{NaOH}$ is a base, it will turn the solution to dark pink, almost purple
• So it is not red in color.
• Hence this option is not correct.

(d) Yellow

• Because $\mathrm{NaOH}$ is a base, it will turn the solution to dark pink, almost purple
• So it is not yellow in color.
• Hence this option is not correct.

Therefore the correct option is (c ). When phenolphthalein is added to $\mathrm{NaOH}$, the color of the solution will become pink.