Qualitative and Quantitative Analysis (Estimation of Carbon, Hydrogen, Nitrogen,... ) NEET Questions

Organic Chemistry - Purification and Characterization of Organic Compounds

Qualitative and Quantitative Analysis (Estimation of Carbon, Hydrogen, Nitrogen,... ) MCQ Questions


13.
Why is acetic acid (and not H2SO4) used to acidify the sodium fusion extract in lead acetate test for sulphur?
A.
Acetic acid is cheaper
B.
H2SO4 oxidises sulphide
C.
Acetic acid is a stronger acid
D.
H2SO4 itself contains sulphur and would react with lead acetate to give white precipitate of PbSO4
😑 View Answer Rough Work Error
ANSWER :
D. H2SO4 itself contains sulphur and would react with lead acetate to give white precipitate of PbSO4
14.
In Lassaigne's test for chlorine, the sodium fusion extract is acidified with HNO3 and treated with AgNO3 to give:
A.
Yellow precipitate insoluble in NH4OH
B.
White precipitate soluble in NH4OH
C.
Yellowish precipitate sparingly soluble in NH4OH
D.
Brown precipitate
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ANSWER :
B. White precipitate soluble in NH4OH
15.
A pale yellow precipitate sparingly soluble in NH4OH on adding AgNO3 to acidified sodium fusion extract indicates the presence of:
A.
Chlorine
B.
Iodine
C.
Bromine
D.
Fluorine
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ANSWER :
C. Bromine
16.
A yellow precipitate completely insoluble in NH4OH formed on addition of AgNO3 to sodium fusion extract (acidified with HNO3) indicates:
A.
Cl
B.
Br
C.
F
D.
I
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ANSWER :
D. I
17.
Why is the sodium fusion extract first boiled with conc. HNO3 before adding AgNO3 when N or S are also present in the compound?
A.
To increase the temperature
B.
To decompose NaCN and Na2S which would otherwise interfere by giving precipitates with AgNO3
C.
To dilute the extract
D.
To oxidise halides
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ANSWER :
B. To decompose NaCN and Na2S which would otherwise interfere by giving precipitates with AgNO3
18.
Why does CCl4 NOT give a white precipitate of AgCl when heated with AgNO3 solution?
A.
Chlorine in CCl4 is covalently bonded and not present as free Cl⁻ ions
B.
AgCl is colourless
C.
CCl4 reacts with AgNO3 to form a soluble complex
D.
AgNO3 decomposes
😑 View Answer Rough Work Error
ANSWER :
A. Chlorine in CCl4 is covalently bonded and not present as free Cl⁻ ions