Question

If the egg shell is treated with solution A and the gas that is evolved turns limewater milky. The solution A is:
1. HCl
2. H₂S
3. KCl
4. HNO₃

Answer 1

Correct Answer - Option 1 : HCl

The correct answer is HCL

• The egg-shells are made up of calcium carbonate (CaCO₃).
• When it reacts with Hydrochloric Acid (HCl) it liberates Carbon dioxide (CO₂) gas which turns lime water milky.
• CaCO3 + 2HCl (Acid) = CaCl₂ (Salt) + H₂O + CO₂ 
• Ca(OH)₂ + CO₂ = CaCO₃ + H₂O
• Calcium carbonate (CaCO3) is used in making stone, marble, toothpaste, chalk, etc.
• Hydrogen sulfide (H2S) is a colourless gas having a strong odour of rotten eggs.
• Potassium chloride (KCl) is odourless and has a white or colourless vitreous crystal.
• It's used in fertilizer, medicine, and food processing.