Question

A blue litmus paper was first dipped in dil. HCl and then in dil. NaOH solution. It was observed that the color of the litmus paper

• A. changed to red.
• B. changed first to red and then to blue.
• C. changed blue to colorless.
• D. remained blue in both the solutions.

Answer 1

The correct option is B

changed first to red and then to blue.

The explanation for the correct option (B):

• The litmus paper is an indicator that is used to determine if a solution is acidic or basic.
• An acidic solution turn blue litmus red while a basic solution turns red litmus blue.
• When a blue-colored litmus paper is dipped in a dilute solution of Hydrochloric acid (HCl), the color of the paper changes from blue to red. This is because HCl is acidic in nature. When the same litmus paper (red color) is dipped in a dilute solution of Sodium hydroxide (NaOH), the color of the paper changes from red to blue. This is because NaOH is basic in nature.
• Thus, the litmus paper first changes its color from blue to red and then from red to blue.

Final Answer: Hence, option (B) is correct. The color of the litmus paper changed first to red and then to blue.