Catalyst Use in Contact Process for Sulfuric Acid

Steps:

• Identify steps in sulfuric acid production: P (S to SO2 via combustion), Q (SO2 to SO3 via oxidation), R (SO3 absorption into H2SO4).
• Recall catalyst role: Only the oxidation step (Q) uses vanadium pentoxide (V2O5) to facilitate SO2 + 1/2 O2 → SO3.
• Confirm no catalysts in P (spontaneous burning) or R (acid absorption).
• Match to options: Catalyst solely in Q, selecting C.

Why C is correct:

• In the contact process, V2O5 catalyst lowers activation energy for the exothermic SO2 oxidation, enabling efficient SO3 production per industrial catalysis principles.

Why the others are wrong:

• A: Incorrectly includes P and R, which involve no catalysts.
• B: Wrongly adds R, an absorption step without catalysis.
• D: Falsely limits to R only, ignoring the key oxidation in Q.

Final answer: C