Which requires catalyst

1.	Which requires catalyst
Answer» `S+O_(2)toSO_(2)` `2SO_(2)+O_(2)to2SO_(3)` `C+O_(2)toCO_(2)` All Solution :`UNDERSET((G))(2SO_(2))+underset((g))(O_(2))underset("ASBESTOS (promoter)")overset("At Catalyst")to2SO_(3)(g)`

Discussion