Compound 'A' reacts with dilute hydrochloric acid to produce effervescence. The gas evolved turns lime water milky. Select the compound A.

Correct option is A

The correct answer is (A)   $$Na_2CO_3$$​​

• The compound sodium carbonate (Na₂CO₃) reacts with dilute hydrochloric acid (HCl) to produce effervescence due to the release of carbon dioxide gas (CO₂).
• When the evolved carbon dioxide gas is passed through lime water, it turns milky due to the formation of calcium carbonate (CaCO₃).​
  

Information booster:

Reaction between sodium carbonate and hydrochloric acid:

$$Na_2CO_3$$ + 2HCl → 2NaCl +$$H_2O$$ + $$CO_2$$

Reaction of carbon dioxide with lime water:

Ca(OH$$)_2$$ + $$CO_2$$ → $$CaCO_3$$↓ +  $$H_2O$$

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​$$H_2O$$

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