the decomposition of ammonia is: 2 nh 3( g) ⇌ n 2( g) 3 h 2( g). if the pressure of ammonia is 1.0 × 10 -3 atm, and the pressures of n 2 and h 2 are each 0.20 atm, what is the value for k p' at 400°c for the reverse reaction? 1.6 × 103 6.2 × 10-4 -6.2 × 10-4 -1.6 × 103