Detection of Extra Elements (Nitrogen, Sulphur, Halogens) in Organic Compounds NEET Questions

Organic Chemistry - Principles of Practical Chemistry

Detection of Extra Elements (Nitrogen, Sulphur, Halogens) in Organic Compounds MCQ Questions


7.
Why is sodium metal dried before fusion in Lassaigne's test?
A.
To make sodium denser
B.
To prevent it from oxidising in air
C.
To avoid explosions due to kerosene oil vapours during heating
D.
To make it react faster with halogens
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ANSWER :
C. To avoid explosions due to kerosene oil vapours during heating
8.
Why is potassium NOT used in place of sodium in Lassaigne's test?
A.
Potassium does not react with organic compounds
B.
Potassium gives wrong colours
C.
Potassium is too expensive
D.
Potassium is too reactive and dangerous to handle
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ANSWER :
D. Potassium is too reactive and dangerous to handle
9.
After sodium fusion, the red-hot fusion tube is plunged into:
A.
Acetone
B.
Cold distilled water in a china dish (porcelain bowl)
C.
Concentrated Hâ‚‚SOâ‚„
D.
Liquid ammonia
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ANSWER :
B. Cold distilled water in a china dish (porcelain bowl)
10.
The sodium fusion extract is usually:
A.
Alkaline (basic)
B.
Strongly acidic
C.
Neutral
D.
Slightly acidic
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ANSWER :
A. Alkaline (basic)
11.
If the sodium fusion extract is not sufficiently alkaline, what is added to make it alkaline?
A.
Concentrated Hâ‚‚SOâ‚„
B.
Acetic acid
C.
Dilute HCl
D.
A few drops of NaOH solution
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ANSWER :
D. A few drops of NaOH solution
12.
What happens chemically when excess sodium reacts with water during preparation of the extract?
A.
It forms sodium peroxide
B.
Nothing happens
C.
It forms NaOH and liberates Hâ‚‚ gas
D.
It forms NaCl and releases Clâ‚‚
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ANSWER :
C. It forms NaOH and liberates Hâ‚‚ gas