The correct option is B 0.315
3Se2(g)⇌ Se6(g)
a - aα aα3
observed moles at equilibriuminitial moles of reactant= MinitMeq
a(1−α) +a α3a = MinitMeq
(1−α) +α3 = MinitMeq
Minit=MSe2= 2× 79=158
Molar mass of mixture Meq=W× R× TP× V
Meq=0.02 × 0.0821× 3001× 2.463×10−3
Meq=200
∴α=0.315