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Q92 (NDA-II/2010) Science & Technology β€Ί Basic Science (Physics, Chemistry, Biology) β€Ί Basic chemical principles Answer Verified

A mixture containing Si02, NaCl and NH4C1 is taken for separating the constituents. The suitable steps required for this are

Result
Your answer: β€”  Β·  Correct: A
Explanation

To separate a mixture of SiO2 (silica), NaCl (sodium chloride), and NH4Cl (ammonium chloride), the first step is sublimation. Ammonium chloride (NH4Cl) is a volatile solid that undergoes sublimation upon heating, allowing it to be collected as a gas and separated from the non-volatile components [t2][t5]. The remaining residue contains SiO2 and NaCl. The next step is dissolution, where water is added to the mixture; NaCl is highly soluble in water, while SiO2 is insoluble [t1][t4]. Filtration is then employed to separate the insoluble SiO2 (residue) from the aqueous NaCl solution (filtrate) [t2]. Finally, the NaCl is recovered from the solution through crystallisation or evaporation, where the solvent is removed to leave behind pure salt crystals [t1][t6]. This sequence ensures each component is isolated based on its unique physical properties: volatility, solubility, and particle size.

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