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Redox Reactions · Question 2

JEE Main 2026 (Online) 4th April Morning ShiftMCQMedium📈 Topic in 13% papers+4−1
1

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

Answer

(2) 2

Solution

In acidic medium: MnO4- + 8H+ + 5e- Mn2+ + 4H2O (each KMnO4 takes 5 e-)

Oxidisable parts: Fe2+ Fe3+ + e- and C2O42- 2CO2 + 2e-

FeC2O4: 1 ( Fe2+) + 2 (one oxalate) = 3 mol e-

Fe2(C2O4)3: Fe already +3; 3 oxalates × 2 = 6 mol e-

FeSO4: 1 mol e-

Fe2(SO4)3: nothing to oxidise = 0

⇒ Total electrons lost = 3 + 6 + 1 + 0 = 10 mol

∴ Moles of KMnO4 = 105 = 2

Answer: (2)

JEE Main 2026 (Online) 4th April Morning Shift

Keep practising — Redox Reactions

2

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
3

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)

JEE Main 2026 (Online) 28th January Morning Shift
4

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 .

JEE Main 2026 (Online) 24th January Morning Shift
5

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 = .

JEE Main 2026 (Online) 23rd January Evening Shift
6

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
JEE Main 2025 (Online) 28th January Morning Shift

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