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Science — CBSE Class 10 board question

Q1. [1]
When Sodium bicarbonate reacts with dilute hydrochloric acid, the gas evolved is :
  1. (a) Hydrogen; it gives pop sound with burning match stick.
  2. (b) Hydrogen; it turns lime water milky.
  3. (c) Carbon dioxide; it turns lime water milky.
  4. (d) Carbon dioxide; it blows off a burning match stick with a pop sound.
Previously asked in CBSE board exam
2023 31/4/1 Q1
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer

(c) Carbon dioxide; it turns lime water milky.

NaHCO₃ + HCl → NaCl + H₂O + CO₂. CO₂ is evolved, which turns lime water milky.

Explanation

When an acid reacts with a metal hydrogencarbonate (bicarbonate), it produces CO₂ gas (not hydrogen). CO₂ turns lime water milky — this is its standard test. Option (d) is wrong because CO₂ does not cause a pop sound; that test is for hydrogen gas.

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