Why does effervescence occur when acid is added to sodium hydrogen carbonate?
Answer and explanation
Correct answer: Due to formation of carbon dioxide gas
The governing concept is gas evolution in an acid–hydrogen carbonate reaction. Sodium hydrogen carbonate reacts with an acid to form a salt, water, and carbon dioxide; for example, NaHCO₃ + HCl → NaCl + H₂O + CO₂. The rapid escape of CO₂ bubbles produces effervescence. Therefore option A is correct. No gas freezes, water does not become solid, and the salt is not burning.
Frequently asked questions
What is the correct answer to this question?
Due to formation of carbon dioxide gas
Why is this the correct answer?
The governing concept is gas evolution in an acid–hydrogen carbonate reaction. Sodium hydrogen carbonate reacts with an acid to form a salt, water, and carbon dioxide; for example, NaHCO₃ + HCl → NaCl + H₂O + CO₂. The rapid escape of CO₂ bubbles produces effervescence. Therefore option A is correct. No gas freezes, water does not become solid, and the salt is not burning.
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.
