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Redox Reactions

JEE Main 2026 (Online) 6th April Evening ShiftNumericalMedium📈 Topic in 9% papers+4
Ques. 1JEE Main 2026, 6 April (Evening Shift)

500 mL of 0.2 M MnO4- solution in basic medium when mixed with 500 mL of 1.5 M KI solution, oxidises iodide ions to liberate molecular iodine. This liberated iodine is then titrated with a standard x M thiosulphate solution in presence of starch till the end point. If 300 mL of thiosulphate was consumed, then the value of x is .

Answer

1

Solution

In basic medium, MnO4- + 2H2O + 3e- MnO2 + 4OH- and 2I- I2 + 2e-.

n(MnO4-) = 0.5 × 0.2 = 0.1 mol, so it accepts 0.3 mol of electrons.

n(I-) = 0.5 × 1.5 = 0.75 mol, which is in excess (only 0.3 mol is needed), so

n(I2) = 0.32 = 0.15 mol

From I2 + 2S2O32- 2I- + S4O62-, n( S2O32-) = 2 × 0.15 = 0.3 mol, hence

x = 0.3 mol0.300 L = 1 M

Answer: 1

Keep practising — Redox Reactions

Ques. 2JEE Main 2026, 4 April (Morning Shift)

In order to oxidise a mixture of 1 mole each of FeC2O4, Fe2(C2O4)3, FeSO4 and Fe2(SO4)3 in acidic medium, the number of moles of KMnO4 required is

  1. 3
  2. 2
  3. 5
  4. 7
Ques. 3JEE Main 2026, 2 April (Morning Shift)

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
Ques. 4JEE Main 2026, 28 January (Morning Shift)

500 mL of 1.2 M KI solution is mixed with 500 mL of 0.2 M KMnO4 solution in basic medium. The liberated iodine was titrated with standard 0.1 M Na2S2O3 solution in the presence of starch indicator till the blue color disappeared. The volume (in L) of Na2S2O3 consumed is . (Nearest integer)

Ques. 5JEE Main 2026, 24 January (Morning Shift)

X and Y are the number of electrons involved, respectively during the oxidation of I- to I2 and S2- to S by acidified K2Cr2O7. The value of X + Y is .

Ques. 6JEE Main 2026, 23 January (Evening Shift)

200 cc of x 10-3 M potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here x = .

Ques. 7JEE Main 2025, 28 January (Morning Shift)

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

  1. A-III, B-IV, C-I, D-II
  2. A-IV, B-I, C-II, D-III
  3. A-II, B-III, C-I, D-IV
  4. A-II, B-III, C-IV, D-I
Ques. 8JEE Main 2025, 22 January (Evening Shift)

The species which does not undergo disproportionation reaction is :

  1. ClO4-
  2. ClO3-
  3. ClO-
  4. ClO2-
Ques. 9JEE Main 2024, 9 April (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. Statement I is correct but Statement II is incorrect
  2. Both Statement I and Statement II are correct
  3. Statement I is incorrect but Statement II is correct
  4. Both Statement I and Statement II are incorrect
Ques. 10JEE Main 2024, 8 April (Morning Shift)

Thiosulphate reacts differently with iodine and bromine in the reactions given below: 2S2O32- + I2 S4O62- + 2I- S2O32- + 5Br2 + 5H2O 2SO42- + 4Br- + 10H+ Which of the following statements justifies the above dual behaviour of thiosulphate?

  1. Thiosulphate undergoes oxidation by bromine and reduction by iodine in these reactions
  2. Bromine is a weaker oxidant than iodine
  3. Bromine is a stronger oxidant than iodine
  4. Bromine undergoes oxidation and iodine undergoes reduction in these reactions
Ques. 11JEE Main 2024, 6 April (Evening Shift)

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

  1. A-IV, B-I, C-II, D-III
  2. A-I, B-II, C-III, D-IV
  3. A-II, B-III, C-IV, D-I
  4. A-III, B-II, C-I, D-IV

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