Question

Assertion :Addition of ammonium chloride to a solution containing ferric and magnesium ions is essential for selective precipitation of ferric hydroxide by aqueous ammonia. Reason: The function of $N{H}_{4}Cl$ is to supress the ionization of $N{H}_{4}OH$ by common ion effect and thus prevents the precipitation of $Mg(OH{)}_2$ because $K_{sp}$of $Mg(OH{)}_2$ is high.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is incorrect but Reason is correct
• D. Both Assertion and Reason are correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Addition of ammonium chloride to a solution containing ferric and magnesium ions is essential for selective precipitation of ferric hydroxide by aqueous ammonia as the function of $N{H}_{4}Cl$ is to suppress the ionization of $N{H}_{4}OH$ by common ion effect and thus prevents the precipitation of $Mg(OH{)}_2$ because $K_{sp}$ of $Mg(OH{)}_2$ is high. Thus, in the third group iron is precipitated as ferric hydroxide first.