Answer: D
Moles: NX2OX4 = 0.368/92 = 0.0040 mol, NOX2 = 0.368/46 = 0.0080 mol, so concentrations are 0.0040 and 0.0080 mol/L. Kc=Kp/RT=0.15/(0.0821×300)=0.0061. Qc=(0.0080)2/0.0040=0.016. Since Qc>Kc, the net change is backward. Comparing Qc with Kp directly is wrong because they differ by the factor RT.