An acid solution of pH equal to three is gradually diluted with water. As a result of this dilution, the pH of the solution will
[amp_mcq option1=”reach near to zero.” option2=”reach near to fourteen.” option3=”reach near to seven.” option4=”remain unchanged.” correct=”option3″]
This question was previously asked in
UPSC CISF-AC-EXE – 2018
An acid solution with pH = 3 has a relatively high concentration of H+ ions. Diluting this solution with pure water (which has a neutral pH of 7) reduces the concentration of the acid, and thus the concentration of H+ ions from the acid. The total concentration of H+ ions approaches the concentration of H+ ions in pure water (which is $10^{-7}$ M at 25°C, corresponding to pH 7). As the concentration of H+ decreases, the pH value (which is -log[H+]) increases. The pH will move from 3 towards 7, but it will not exceed 7 when diluting with pure water.
Diluting an acidic solution with neutral water increases its pH, moving it towards 7.