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Principles Related to Practical Chemistry · Question 46

JEE Main 2025 (Online) 3rd April Evening ShiftMCQMedium📈 Topic in 16% papers+4−1
1

Compounds that should not be used as primary standards in titrimetric analysis are : Choose the most appropriate answer from the options given below:

  1. C, D and E Only
  2. B and D Only
  3. D and E Only
  4. A, C and D Only

Answer

(4) A, C and D Only

Solution

A primary standard should be available in pure form, should not be hygroscopic or efflorescent, should not react with air (O2, CO2) and should have a fixed composition.

A. Na2Cr2O7 is hygroscopic (hence K2Cr2O7 is used instead). Not a primary standard.

B. Oxalic acid (H2C2O4 2H2O) is a primary standard.

C. NaOH is hygroscopic and absorbs CO2 from air. Not a primary standard.

D. Hydrated ferrous sulphate loses water of crystallisation and is oxidised by air to Fe(III) (Mohr's salt is used instead). Not a primary standard.

E. Sodium tetraborate (borax, Na2B4O7 10H2O) is a primary standard.

A, C and D only.

Answer: (4)

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2

In Dumas' method for estimation of nitrogen 0.4 g of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound is (Given : Aqueous tension at 300 K = 15 mm Hg)

  1. 15.71\%
  2. 17.46\%
  3. 7.85\%
  4. 20.95\%
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3

Choose the correct tests with respective observations. Choose the correct answer from the options given below :

  1. A, D and E only
  2. A, B and C only
  3. B, D and E only
  4. C, D and E only
JEE Main 2025 (Online) 2nd April Morning Shift
4

In Dumas' method for estimation of nitrogen, 0.5 gram of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound (Aqueous tension at 300 K = 15 mm Hg) is %.

  1. 20.87
  2. 12.57
  3. 1.257
  4. 18.67
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5

Formation of Na4[Fe(CN)5NOS], a purple coloured complex formed by addition of sodium nitroprusside in sodium carbonate extract of salt indicates the presence of:

  1. Sulphide ion
  2. Sulphite ion
  3. Sulphate ion
  4. Sodium ion
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6

Match List-I with List-II. Choose the correct answer from the options given below:

  1. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
  2. (A)-(III), (B)-(IV), (C)-(II), (D)-(I)
  3. (A)-(II), (B)-(IV), (C)-(I), (D)-(III)
  4. (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
JEE Main 2025 (Online) 2nd April Evening Shift
7

The steam volatile compounds among the following are : Choose the correct answer from the options given below :

  1. (B) and (D) Only
  2. (A), (B) and (C) Only
  3. (A) and (B) Only
  4. (A) and (C) Only
JEE Main 2025 (Online) 29th January Morning Shift
8

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

  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Both Statement I and Statement II are false
JEE Main 2025 (Online) 28th January Morning Shift
9

The metal ion whose electronic configuration is not affected by the nature of the ligand and which gives a violet colour in non-luminous flame under hot condition in borax bead test is

  1. Cr3+
  2. Ti3+
  3. Ni2+
  4. Mn2+
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10

The purification method based on the following physical transformation is : (X)Solid Heat (X)Vapour Cool (X)Solid

  1. Extraction
  2. Crystallization
  3. Distillation
  4. Sublimation
JEE Main 2025 (Online) 28th January Evening Shift
11

Identify the inorganic sulphides that are yellow in colour : Choose the correct answer from the options given below :

  1. (D) and (E) only
  2. (A) and (B) only
  3. (A), (D) and (E) only
  4. (A) and (C) only
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