Chemical Principles Involved in the Qualitative Salt Analysis - Cations and Anions NEET Questions

Organic Chemistry - Principles of Practical Chemistry

Chemical Principles Involved in the Qualitative Salt Analysis - Cations and Anions MCQ Questions


7.
In group IV analysis, NH4Cl + NH4OH is added before passing H2S so that:
A.
All sulphides become soluble
B.
Group IV cations get oxidised
C.
Coloured complexes are produced
D.
[S2-] becomes high enough (alkaline medium) to exceed Ksp of group IV sulphides which have larger Ksp
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ANSWER :
D. [S2-] becomes high enough (alkaline medium) to exceed Ksp of group IV sulphides which have larger Ksp
8.
Why is concentrated HCl NOT used as the group reagent for Group I (in place of dilute HCl)?
A.
Concentrated HCl reacts with the test tube
B.
Because PbCl2 dissolves in concentrated HCl forming a soluble [PbCl4]2- complex
C.
Lead is not in Group I; it is in Group V
D.
Concentrated HCl is too volatile
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ANSWER :
B. Because PbCl2 dissolves in concentrated HCl forming a soluble [PbCl4]2- complex
9.
Why is lead (Pb2+) reported in BOTH group I and group II of the analytical scheme?
A.
PbCl2 has a moderately low Ksp, so part of the Pb2+ remains in solution and gets precipitated as PbS in group II
B.
Pb2+ is amphoteric
C.
Pb2+ has two oxidation states
D.
Lead occurs only as a contaminant
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ANSWER :
A. PbCl2 has a moderately low Ksp, so part of the Pb2+ remains in solution and gets precipitated as PbS in group II
10.
Which of the following is NOT a group reagent in qualitative cation analysis?
A.
Dilute HCl (Group I)
B.
(NH4)2CO3 in NH4Cl + NH4OH (Group V)
C.
H2S in dilute HCl (Group II)
D.
Aqua regia
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ANSWER :
D. Aqua regia
11.
Which of the following is the group reagent for Group III cations (Fe3+, Al3+, Cr3+)?
A.
(NH4)2CO3 in NH4OH
B.
H2S in HCl
C.
NH4Cl + NH4OH (excess)
D.
Dilute HCl
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ANSWER :
C. NH4Cl + NH4OH (excess)
12.
Group II cations are precipitated by H2S in:
A.
Alkaline medium (NH4OH)
B.
Acidic medium (dilute HCl)
C.
Neutral medium
D.
Concentrated HNO3
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ANSWER :
B. Acidic medium (dilute HCl)