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 .
Redox Reactions
Previous year questions with solutions · 2025 – 2026
7Questions
7Papers covered
1.26% ↑278.9%Weightage in 2026
’25
’26
Year-wise statistics questions · papers · average per paper · weightage
| Year | Questions | Papers | Avg / paper | Weightage |
|---|---|---|---|---|
| 2026 | 6 | 19 | 0.32 | 1.26% ↑278.9% |
| 2025 | 1 | 12 | 0.083 | 0.33% |
1
JEE Main 2026 (Online) 6th April Evening Shift
2
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
3
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
4
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