NEETChemistryp Block Elements (Group 15, 16, 17 & 18)
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In the Ostwald process, the nitric oxide ( NO ) gas formed in the final absorption tower is recycled back into the process. Reason (R): Aqueous nitric acid obtained by the absorption of NO ₂ in water can be concentrated to 98 % by mass using simple distillation. In the light of the above statements
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
C. (A) is correct but (R) is not correct
Step-by-step solution
Assertion (A) is correct. In the final step of the Ostwald process, nitrogen dioxide is absorbed in water to form nitric acid and nitric oxide: 3 NO ₂( g ) + H ₂ O ( l ) 2 HNO ₃( aq ) + NO ( g ) The NO gas thus formed is recycled and re-oxidised to NO ₂ . Reason (R) is incorrect. Aqueous nitric acid obtained by this method can be concentrated by distillation only up to 68 % by mass, as it forms a constant boiling mixture (azeotrope) with water. Further concentration to 98 % requires dehydration with concentrated H