How Many Grams of Potassium Chlorate, KClO₃, Decompose to Form

How many grams of potassium chlorate, KClO₃, decompose to form potassium chloride and 250. mL of O₂ at 400 K and 0.850 atm?
Molar Mass(KClO₃) = 122.55 g/mol 2 KClO₃ (s) →2 KCl (s) + 3 O₂ (g)

A) 0.00647 g O₂
B) 0.529 g O₂
C) 0.793 g O₂
D) 1.19 g O₂
E) 4.76 g O₂