A substance dissolves in water, turns red litmus blue, and feels soapy. Which ion will mainly be present?
Answer and explanation
Correct answer: Hydroxide ion
The governing concept is the identification of bases through their properties and ions in aqueous solution. A base changes red litmus to blue and often feels slippery or soapy, indicating the presence of hydroxide ions, OH⁻, in water. Therefore option A is correct. Hydrogen ions are associated with acidic solutions and would turn blue litmus red. Chloride ions alone are not responsible for basicity, and carbonate is not always the principal ion in every base.
Frequently asked questions
What is the correct answer to this question?
Hydroxide ion
Why is this the correct answer?
The governing concept is the identification of bases through their properties and ions in aqueous solution. A base changes red litmus to blue and often feels slippery or soapy, indicating the presence of hydroxide ions, OH⁻, in water. Therefore option A is correct. Hydrogen ions are associated with acidic solutions and would turn blue litmus red. Chloride ions alone are not responsible for basicity, and carbonate is not always the principal ion in every base.
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.
