MolSynapsequestion bank

MolSynapse / Question bank / Qualitative Analysis: Cations / Group reagents and group separation logic

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3qc037

The filtrate from group II contains $Fe X^{2 +}$ (formed by reduction with $H X_{2} S$ ) and is to be analysed for group III. Select the correct statements.

ABoiling with a few drops of concentrated $HNO X_{3}$ oxidises $Fe X^{2 +}$ to $Fe X^{3 +}$ , so that iron is precipitated as $Fe (OH) X_{3}$ .
BBoiling converts $Mn X^{2 +}$ into $MnO X_{2}$ , which is separated first.
C $H X_{2} S$ must be boiled off, otherwise group IV sulphides would precipitate with the group III residue.
DConcentrated $HNO X_{3}$ at this stage converts residual $Pb X^{2 +}$ into insoluble $PbSO X_{4}$ .

Answer: A, C

Hot concentrated

HNO X_{3}

destroys residual

H X_{2} S

and converts

Fe X^{2 +}

to

Fe X^{3 +}

, as required for

Fe (OH) X_{3}

. No sulphate is present to form

PbSO X_{4}

, and

Mn X^{2 +}

is not oxidised by boiling in acid.

Practice Qualitative Analysis: Cations More on Group reagents and group separation logic

Previous questionNext question

More questions on Group reagents and group separation logic

A solution is 0.015 M in Zn^2+ and is kept saturated with H2S ([H2S] = 0.10 M throughout). For the overall ionisation H2S <=> 2H+ + S^2- tak... JEE Advanced level
Select the correct statements about the use of HCl and H2S in the group II separation. JEE Advanced level
For the group III separation, which of the following statements are correct? JEE Advanced level
A solution is 0.30 M in HCl, saturated with H2S (0.10 M), and contains each of Cd^2+, Cu^2+, Zn^2+ and Ni^2+ at 0.010 M. Use K = [H+]^2[S^2-... JEE Advanced level
Regarding the group VI cation Mg^2+, which statements are correct? JEE Advanced level
Select the correct statements about the test for ammonium ion. JEE Advanced level