A student adds sodium hydroxide solution to an acidic solution to increase its pH. Which statement is correct during this process?
Answer and explanation
Correct answer: The hydrogen-ion concentration decreases and the solution moves towards neutrality.
Sodium hydroxide is a strong base and dissociates to provide OH⁻ ions. These ions react with hydrogen ions from the acid: H⁺ + OH⁻ → H₂O. Consequently, the hydrogen-ion concentration decreases and the pH rises, initially moving the solution towards neutrality. Sodium hydroxide is not an acid, and a pH change does not require adding pure water separately. Thus, option A is correct.
Frequently asked questions
What is the correct answer to this question?
The hydrogen-ion concentration decreases and the solution moves towards neutrality.
Why is this the correct answer?
Sodium hydroxide is a strong base and dissociates to provide OH⁻ ions. These ions react with hydrogen ions from the acid: H⁺ + OH⁻ → H₂O. Consequently, the hydrogen-ion concentration decreases and the pH rises, initially moving the solution towards neutrality. Sodium hydroxide is not an acid, and a pH change does not require adding pure water separately. Thus, option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
