An unknown solution turns blue litmus red and gives a gas with zinc. When sodium carbonate is added to the same solution, another gas is released. What is the correct identification of both gases?
Answer and explanation
Correct answer: Hydrogen from zinc and carbon dioxide from carbonate
Blue litmus turning red establishes that the unknown solution is acidic. Acids react with zinc, an active metal, to form a salt and hydrogen gas: acid + Zn → salt + H2. The same acid reacts with sodium carbonate to form a salt, water, and carbon dioxide: acid + carbonate → salt + H2O + CO2. Therefore option A correctly identifies the two gases.
Frequently asked questions
What is the correct answer to this question?
Hydrogen from zinc and carbon dioxide from carbonate
Why is this the correct answer?
Blue litmus turning red establishes that the unknown solution is acidic. Acids react with zinc, an active metal, to form a salt and hydrogen gas: acid + Zn → salt + H2. The same acid reacts with sodium carbonate to form a salt, water, and carbon dioxide: acid + carbonate → salt + H2O + CO2. Therefore option A correctly identifies the two gases.
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.
