Which from following activities results in to the formation of oleum in manufacture of sulphuric acid…

Which from following activities results in to the formation of oleum in manufacture of sulphuric acid contact process?
  1. By adding sodium sulphite and $\mathrm{SO}_2$ in water
  2. By passing $\mathrm{SO}_2$ gas in to the dil. $\mathrm{H}_2 \mathrm{SO}_4$
  3. Passing $\mathrm{SO}_2$ gas through $\mathrm{NaOH}$ solution
  4. By absorbing $\mathrm{SO}_3$ gas in conc. $\mathrm{H}_2 \mathrm{SO}_4$

Solution

Constant volume process is isochoric process

Asked in: MHT CET 2022 (11 Aug Shift 1)

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