By which test can the gas formed at the cathode in the chlor-alkali process be identified?
Answer and explanation
Correct answer: By giving a pop sound near a burning splint
In the chlor-alkali process, concentrated aqueous sodium chloride is electrolysed. Water is reduced at the cathode, producing hydrogen gas: 2H₂O + 2e⁻ → H₂ + 2OH⁻. Hydrogen is combustible and, when a small sample is brought near a burning splint, it burns with a characteristic ‘pop’ sound. Therefore option B identifies the cathode gas. Limewater tests carbon dioxide, while the litmus and turmeric changes are not the hydrogen test.
Frequently asked questions
What is the correct answer to this question?
By giving a pop sound near a burning splint
Why is this the correct answer?
In the chlor-alkali process, concentrated aqueous sodium chloride is electrolysed. Water is reduced at the cathode, producing hydrogen gas: 2H₂O + 2e⁻ → H₂ + 2OH⁻. Hydrogen is combustible and, when a small sample is brought near a burning splint, it burns with a characteristic ‘pop’ sound. Therefore option B identifies the cathode gas. Limewater tests carbon dioxide, while the litmus and turmeric changes are not the hydrogen test.
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.
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