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Principles Related to Practical Chemistry · Question 23

AIPMT 2014MCQMedium📈 Topic in 25% papers+4−1
1

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

Answer

(1) 37.33

Solution

2NH3 + H2SO4 (NH4)2SO4

Moles of H2SO4 = 10 11000 = 0.01 mol

⇒ moles of NH3 = 2 0.01 = 0.02 mol = moles of N

Mass of N = 0.02 14 = 0.28 g

% N = 0.280.75 100

= 37.33\%

Answer: (1)

AIPMT 2014

Keep practising — Principles Related to Practical Chemistry

2

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)
3

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)
4

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)
5

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
6

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
7

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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