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Principles Related to Practical Chemistry · Question 21

NEET 2017MCQEasy📈 Topic in 50% papers+4−1
1

The most suitable method of separation of 1 : 1 mixture of ortho and para-nitrophenols is

  1. chromatography
  2. crystallisation
  3. steam distillation
  4. sublimation.

Answer

(3) steam distillation

Solution

o-Nitrophenol has intramolecular hydrogen bonding ⇒ no association ⇒ it is volatile in steam.

p-Nitrophenol has intermolecular hydrogen bonding ⇒ associated molecules ⇒ less volatile.

As per NCERT, the mixture of o- and p-nitrophenols is separated by steam distillation; o-nitrophenol distils over with steam.

Answer: (3)

NEET 2017

Keep practising — Principles Related to Practical Chemistry

2

In Dumas method for estimation of nitrogen, 0.25 g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm pressure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is

  1. 16.75
  2. 15.76
  3. 17.36
  4. 18.20
AIPMT 2015 (Cancelled)
3

In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralized 10 mL of 1 M H2SO4. The percentage of nitrogen in the soil is

  1. 37.33
  2. 45.33
  3. 35.33
  4. 43.33
AIPMT 2014
4

Nitrogen detection in an organic compound is carried out by Lassaigne's test. The blue colour formed corresponds to which of the following formulae?

  1. Fe3[Fe(CN)6]2
  2. Fe4[Fe(CN)6]3
  3. Fe4[Fe(CN)6]2
  4. Fe3[Fe(CN)6]3
NEET 2013 (Karnataka)
5

The Lassaigne's extract is boiled with conc. HNO3 while testing for halogens. By doing so it

  1. decomposes Na2S and NaCN, formed
  2. helps in the precipitation of AgCl
  3. increases the solubility product of AgCl
  4. increases the concentration of NO3- ions
AIPMT 2011 (Prelims)
6

In Dumas method of estimation of nitrogen, 0.35 g of an organic compound gave 55 mL of nitrogen collected at 300 K temperature and 715 mm pressure. The percentage composition of nitrogen in the compound would be (aqueous tension at 300 K = 15 mm).

  1. 15.45
  2. 16.45
  3. 17.45
  4. 14.45
Out of syllabusAIPMT 2011 (Prelims)
7

The best method for the separation of naphthalene and benzoic acid from their mixture is

  1. distillation
  2. sublimation
  3. chromatography
  4. crystallisation.
AIPMT 2005
8

Which of the following is incorrect?

  1. FeCl3 is used in detection of phenol.
  2. Fehling's solution is used in detection of glucose.
  3. Tollens' reagent is used in detection of unsaturation.
  4. NaHSO3 is used in detection of carbonyl compound.
AIPMT 2001
9

In steam distillation of toluene, the pressure of toluene in vapour is

  1. equal to pressure of barometer
  2. less than pressure of barometer
  3. equal to vapour pressure of toluene in simple distillation
  4. more than vapour pressure of toluene in simple distillation.
AIPMT 2001

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