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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3qc218

For the group V precipitation by $(NH X_{4}) X_{2} CO X_{3}$ , which conditions are correct?

Athe medium must be ammoniacal so that $CO X_{3} X^{2 -}$ is not converted to $H X_{2} CO X_{3}$
Bthe mixture should not be heated strongly because $(NH X_{4}) X_{2} CO X_{3}$ decomposes to $NH X_{3}$ and $CO X_{2}$
C $NH X_{4} Cl$ is added so that $Mg X^{2 +}$ is not precipitated
Dthe reagent is added in the presence of dilute HCl

Answer: A, B, C

Acid would destroy carbonate, so the medium is ammoniacal and not acidic. Strong heating decomposes ammonium carbonate;

NH X_{4} Cl

prevents

Mg X^{2 +}

carbonate precipitation. Hence 1, 2 and 3.

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