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


13.
Group IV cations are precipitated by H2S in:
A.
Alkaline medium (NH4Cl + NH4OH)
B.
Concentrated H2SO4
C.
Acidic medium (dilute HCl)
D.
Aqua regia
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ANSWER :
A. Alkaline medium (NH4Cl + NH4OH)
14.
Group V cations are precipitated as:
A.
Hydroxides by NH4OH alone
B.
Chlorides by HCl
C.
Sulphides by H2S in HCl
D.
Carbonates by (NH4)2CO3 in NH4Cl + NH4OH medium
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ANSWER :
D. Carbonates by (NH4)2CO3 in NH4Cl + NH4OH medium
15.
Why is (NH4)2CO3 (and not Na2CO3) used as the group reagent for group V cations?
A.
Na2CO3 reacts with NH4Cl
B.
(NH4)2CO3 is more soluble
C.
Na2CO3 would precipitate Mg2+ from group VI as MgCO3 also
D.
(NH4)2CO3 is cheaper
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ANSWER :
C. Na2CO3 would precipitate Mg2+ from group VI as MgCO3 also
16.
Group VI is identified by reagents specific for:
A.
Pb2+ only
B.
Mg2+ (e.g., disodium hydrogen phosphate Na2HPO4 in NH4OH)
C.
Ba2+ only
D.
Ammonium ion
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ANSWER :
B. Mg2+ (e.g., disodium hydrogen phosphate Na2HPO4 in NH4OH)
17.
Why must Group III hydroxides be precipitated in the presence of NH4Cl, not in pure NH4OH?
A.
NH4Cl is a strong base
B.
NH4Cl makes the hydroxides more soluble
C.
Pure NH4OH does not contain OH-
D.
NH4Cl suppresses ionisation of NH4OH so that hydroxides of higher groups (Mg, Mn, etc.) do NOT precipitate
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ANSWER :
D. NH4Cl suppresses ionisation of NH4OH so that hydroxides of higher groups (Mg, Mn, etc.) do NOT precipitate
18.
Sulphides of which group have the LOWEST solubility products?
A.
Group IV (e.g., ZnS, MnS)
B.
Group VI (Mg)
C.
Group II (e.g., CuS, HgS, As2S3)
D.
Group V (no sulphides — they are carbonates)
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ANSWER :
C. Group II (e.g., CuS, HgS, As2S3)