The Elementary Reaction 2NO₂ (g) → 2NO (G) + O₂ (g)

The elementary reaction
2NO₂ (g) → 2NO (g) + O₂ (g)
Is second order in NO₂ and the rate constant at 501 K is 7.93 × 10^{- 3} M^{- 1}s^{- 1}. The reaction half- life at this temperature when [NO₂]₀ = 0.450 M is s.

A) 126
B) 0.011
C) 3.6 × 10^{- 3}
D) 280
E) 87