JEE Main202126 Feb 2021Morning ShiftChemistryp Block Elements (Group 15, 16, 17 & 18)Actual
On treating a compound with warm dil. H 2 SO 4 , gas X is evolved which turns K 2 Cr 2 O 7 paper acidified with dil. H 2 SO 4 to a green compound Y . X and Y respectively are :
Options
- AX = SO 2 ,   Y = Cr 2 O 3
- BX = SO 2 ,   Y = Cr 2 SO 4 3
- CX = SO 3 ,   Y = Cr 2 SO 4 3
- DX = SO 3 ,   Y = Cr 2 O 3
Correct answer
C. X = SO 3 ,   Y = Cr 2 SO 4 3
Step-by-step solution
Sulfur dioxide gas turns acidified potassium dichromate (VI) solution from orange to green. Chromium is reduced from (VI) to (III) after reaction. SO 2 + dil   H 2 SO 4 ⟶ SO 3 g SO 3 + K 2 Cr 2 O 7 → H 2 SO 4 dil Cr 2 SO 4 3 Hence, On treating a compound with warm dil. H 2 SO 4 , gas X is evolved which turns K 2 Cr 2 O 7 paper acidified with dil. H 2 SO 4 to a green compound Y . X and Y respectively are SO 3 and Cr 2 ( SO 4 ) 3 .