NTA Abhyas JEE Main2020Chemistryd and f Block ElementsPractice
Pick out incorrect statement about K 2 C r 2 O 7 .
Options
- AIt oxidizes acidified solution of H 2 S to S
- BIt oxidizes KI to I 2
- CIt oxidizes HCl to C l 2
- DIt gives oxygen, when treated with cold dil. H 2 S O 4
Correct answer
D. It gives oxygen, when treated with cold dil. H 2 S O 4
Step-by-step solution
Here option D is not correct as oxygen is evolved only when K 2 C r 2 O 7 is heated with conc. H 2 S O 4 . 2 K 2 C r 2 O 7 + 8 H 2 S O 4 → Δ 2 K 2 S O 4 + 2 C r 2 S O 4 3 + 8 H 2 O + 3 O 2 A. C r 2 O 7 2 - + 14 H + + 6 e - → 2 C r 3 + + 7 H 2 O S 2 - → S + 2 e - × 3 B. 2 I - → I 2 + 2 e - C. 2 C l - → C l 2 + 2 e -