If the pH of a solution is brought from 11 close to 7, which ion is being effectively reduced?
Answer and explanation
Correct answer: Hydroxide ion
The governing concept is the relationship between pH and hydroxide concentration in a basic solution. A pH of 11 indicates alkalinity, so hydroxide ions are present in relatively high effective concentration. Bringing the pH closer to 7 means neutralising the base, usually by adding acid; hydrogen ions react with hydroxide ions according to H⁺ + OH⁻ → H₂O. Thus the effective amount of OH⁻ decreases, making option C correct. Chloride and nitrate ions do not determine this change.
Frequently asked questions
What is the correct answer to this question?
Hydroxide ion
Why is this the correct answer?
The governing concept is the relationship between pH and hydroxide concentration in a basic solution. A pH of 11 indicates alkalinity, so hydroxide ions are present in relatively high effective concentration. Bringing the pH closer to 7 means neutralising the base, usually by adding acid; hydrogen ions react with hydroxide ions according to H⁺ + OH⁻ → H₂O. Thus the effective amount of OH⁻ decreases, making option C correct. Chloride and nitrate ions do not determine this change.
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.
