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Principles Related to Practical Chemistry · Question 8

JEE Main 2026 (Online) 5th April Evening ShiftMCQEasy📈 Topic in 16% papers+4−1
1

A paper dipped in a dil. H2SO4 solution of 'X' upon treatment with SO2 gas turns into green. The compound 'X' is :

  1. KI-starch
  2. KMnO4
  3. Pb(CH3COO)2
  4. K2Cr2O7

Answer

(4) K2Cr2O7

Solution

SO2 is a reducing agent. Acidified potassium dichromate (orange) is reduced to Cr3+ (green):

Cr2O72- + 3SO2 + 2H+ 2Cr3+ + 3SO42- + H2O

⇒ the paper turns from orange to green.

Other options: KI-starch paper turns blue with oxidising agents; acidified KMnO4 is decolourised (not green) by SO2; lead acetate paper turns black with H2S.

∴ X = K2Cr2O7

Answer: (4)

JEE Main 2026 (Online) 5th April Evening Shift

Keep practising — Principles Related to Practical Chemistry

2

Identify the colour of compound 'X' in the sequence of the reaction. [figure]

  1. Violet
  2. Green
  3. Red
  4. Colourless
JEE Main 2026 (Online) 4th April Morning Shift
3

2.0 g of a bromo hydrocarbon (X) was subjected to Carius analysis, gave 3.36 g of AgBr. The percentage of carbon in the compound (X) is 26.7%. Total number of carbon atoms in the empirical formula for compound (X) is . (Given molar mass in g mol-1 H : 1, C : 12, Br : 80, Ag : 108)

JEE Main 2026 (Online) 4th April Morning Shift
4

Among Fe3+, Pb2+, Cu2+ and Mn2+, identify the one that gets precipitated out while passing H2S in presence of NH4OH as group reagent. The highest possible oxidation state of the corresponding metal is

  1. +3
  2. +4
  3. +2
  4. +7
JEE Main 2026 (Online) 4th April Evening Shift
5

Match the 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-I, D-II
  3. A-I, B-III, C-II, D-IV
  4. A-I, B-II, C-III, D-IV
JEE Main 2026 (Online) 4th April Evening Shift
6

In sulphur estimation, 2.0 10-3 mol of an organic compound (X) (molar mass 76 g mol-1) gave 0.4813 g of barium sulphate (molar mass 233 g mol-1). The percentage of sulphur in the compound (X) is 10-1 % (Nearest integer)

JEE Main 2026 (Online) 4th April Evening Shift
7

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

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 2nd April Morning Shift
8

Match List - I with List - II.

  1. A-IV, B-II, C-I, D-III
  2. A-IV, B-II, C-III, D-I
  3. A-II, B-IV, C-I, D-III
  4. A-II, B-IV, C-III, D-I
JEE Main 2026 (Online) 2nd April Morning Shift
9

A salt with few drops of conc. HCl gives apple green colour in flame test. The group precipitate of the salt is dissolved in acetic acid and treated with K2CrO4 to give yellow precipitate. When the sodium carbonate extract of the salt solution is heated with conc. HNO3 and ammonium molybdate, it resulted a canary yellow precipitate. The cation and anion present in the salt are respectively,

  1. Ca2+ and SO42-
  2. Ba2+ and PO43-
  3. Mn2+ and PO43-
  4. Ba2+ and SO42-
JEE Main 2026 (Online) 2nd April Morning Shift
10

Complete combustion of X g of an organic compound gave 0.25 g of CO2 and 0.12 g of H2O. If the % of carbon is 25% and of hydrogen is 4.89%, then X = 10-3 g. (Nearest integer) (Molar mass of C, H and O are 12, 1 and 16 g mol-1 respectively.)

  1. 273
  2. 27
  3. 2730
  4. 227
JEE Main 2026 (Online) 2nd April Evening Shift
11

Method used for separation of mixture of products (B and C) obtained in the following reaction is [figure]

  1. simple distillation
  2. sublimation
  3. fractional distillation
  4. steam distillation
JEE Main 2026 (Online) 28th January Morning Shift

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