Question

Which of the following will turn blue litmus solution red?

• A. $C{H}_{3}OH$
• B. $C{H}_{3}COOH$
• C. $C{H}_{3}COOC{H}_3$
• D. $C{H}_4$

Answer 1

Answer: (B)

$C{H}_{3}COOH$

Acids have a general property to release hydrogen ion $H^{+}$ in the solution medium, due to which they turn the blue litmus red.

Dissociation of $C{H}_{3}OH$ (methanol) won't produce enough protons/hydrogen ions to shift the equilibrium towards the acidic side and hence it won't affect the color of the litmus solution.

Acetic acid $\left(C{H}_{3}COOH\right)$ undergoes dissociation to release hydrogen ions which makes it acidic in nature.

Thus, it can change the color of the blue litmus solution to red.

$C{H}_{3}COOH\to C{H}_{3}CO{O}^{-1}+H^{+}$

However, in the case of $C{H}_{3}COOC{H}_3$ and $C{H}_4$, the hydrogen atoms are covalently bonded to the carbon atoms and hence they are not released as hydrogen ions in the solution, thus they do not change the color of the litmus solution

Hence, the correct answer is an option ($B$).