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JEE Main · 2020 · 03 Sep 2020 · Shift 1 · Practical and Analytical Chemistry

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The Kjeldahl method of Nitrogen estimation fails for which of the following reaction products?
(a)
(see structure)
(b)
(see structure)
(c)
(see structure)
(d)
(see structure)
Structure a
a
Structure b
b
Structure c
c
Structure d
d
  1. (A)(c) and (d)✓ Correct
  2. (B)(b) and (c)
  3. (C)(a) and (d)
  4. (D)(a), (c) and (d)

Answer: (A)

Solution

The Kjeldahl method works only when the nitrogen is converted to ammonium sulphate during acid digestion, which fails for nitrogen held in a nitro or azo linkage, in a nitrile group, or in a ring, since such nitrogen is not released as ammonia. Among the given products, the two in which the nitrogen is locked in such an environment cannot be estimated by this method.

JEE Main · 2020 · 03 Sep 2020 · Shift 1 · Single correct option

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