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Principles Related to Practical Chemistry

JEE Main 2024 (Online) 4th April Morning ShiftMCQEasy📈 Topic in 41% papers+4−1
Ques. 1JEE Main 2024, 4 April (Morning Shift)

In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to :

  1. decrease concentration of -OH ions
  2. increase concentration of Cl- ions
  3. prevent interference by phosphate ions
  4. increase concentration of NH4+ ions

Answer

(1) decrease concentration of -OH ions

Solution

NH4Cl NH4+ + Cl- (strong electrolyte)

NH4OH NH4+ + OH- (weak base)

∵ Common ion NH4+ suppresses ionisation of NH4OH ⇒ [OH-] decreases

⇒ only group III hydroxides (Fe(OH)3, Al(OH)3, Cr(OH)3; very low Ksp) precipitate; Zn2+, Mn2+, Mg2+ hydroxides do not.

Answer: (1)

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Ques. 2JEE Main 2024, 4 April (Morning Shift)

Which of the following nitrogen containing compound does not give Lassaigne's test ?

  1. Glycine
  2. Phenyl hydrazine
  3. Urea
  4. Hydrazine
Ques. 3JEE Main 2024, 4 April (Evening Shift)

When MnO2 and H2SO4 are added to a salt (A), a greenish yellow gas is liberated. The salt (A) is :

  1. NH4Cl
  2. CaI2
  3. KNO3
  4. NaBr
Ques. 4JEE Main 2024, 4 April (Evening Shift)

The adsorbent used in adsorption chromatography is/are - Choose the most appropriate answer from the options given below :

  1. C and D only
  2. A only
  3. B only
  4. A and B only
Ques. 5JEE Main 2024, 1 February (Morning Shift)

In Kjeldahl's method for estimation of nitrogen, CuSO4 acts as :

  1. catalytic agent
  2. hydrolysis agent
  3. reducing agent
  4. oxidising agent
Ques. 6JEE Main 2024, 1 February (Morning Shift)

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Both Statement I and Statement II are correct
  2. Statement I is incorrect but Statement II is correct
  3. Both Statement I and Statement II are incorrect
  4. Statement I is correct but Statement II is incorrect
Ques. 7JEE Main 2024, 1 February (Morning Shift)

The number of white coloured salts, among the following is (a) SrSO4 (b) Mg(NH4)PO4 (c) BaCrO4 (d) Mn(OH)2 (e) PbSO4 (f) PbCrO4 (g) AgBr (h) PbI2 (i) CaC2O4 (j) [Fe(OH)2(CH3COO)]

Ques. 8JEE Main 2024, 1 February (Evening Shift)

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Statement I is false but Statement II is true
  2. Both Statement I and Statement II are true
  3. Statement I is true but Statement II is false
  4. Both Statement I and Statement II are false
Ques. 9JEE Main 2024, 1 February (Evening Shift)

Lassaigne's test is used for detection of :

  1. Phosphorous and halogens only
  2. Nitrogen, Sulphur and Phosphorous only
  3. Nitrogen, Sulphur, phosphorous and halogens
  4. Nitrogen and Sulphur only
Ques. 10JEE Main 2024, 1 February (Evening Shift)

Following Kjeldahl's method, 1 g of organic compound released ammonia, that neutralised 10 mL of 2 M H2SO4. The percentage of nitrogen in the compound is %.

Ques. 11JEE Main 2024, 31 January (Morning Shift)

The compound that is white in color is

  1. ammonium sulphide
  2. ammonium arsenomolybdate
  3. lead iodide
  4. lead sulphate

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