Choose the Best Answer · Q19
Q.A colourless solid substance (A) on heating evolved CO₂ and also gave a white residue, soluble in water. Residue also gave CO₂ when treated with dilute HCl.
a) Na₂CO₃
b) NaHCO₃
c) CaCO₃
d) Ca(HCO₃)₂
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Start your 14-day free trial to unlock the full solution →Step 1. Substance (A) evolves CO₂ on heating and leaves a white residue that is soluble in water -- heating sodium bicarbonate does exactly this: 2NaHCO₃ →(Δ)→ Na₂CO₃ + H₂O + CO₂, leaving water-soluble Na₂CO₃ as the residue.
Step 2. The residue also evolves CO₂ when treated with dilute HCl: Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂ -- consistent with the residue being a carbonate. …
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