The most stable oxide of nitrogen will be:
a. 2NO(g)⇌N₂(g)+O₂(g) ; K = 2.2 × 10³⁰
b. 2N2₂O(g)⇌2N₂(g)+O₂(g); K = 3.5 × 10³⁰
c. NO₂(g)⇌2NO(g)+O₂(g); K = 6.7 × 10¹⁶
d. 2N₂O₅(g)⇌2N₂(g)+O₂(g) ; K = 1.2 × 10²⁴