2AB4⇋A2(g)+4B2(g)t=0 1 0 0
t=equilibrium 1−2α α 4α
where,2α=x
Degree of dissociation is x.(small compared to unity)
Total pressure is P.
Kp=P.PA2×(P.PB2)4(P.PAB4)2
Total number of moles is equal to 1+3x2
Here x is very very small than 1.
Kp=x2×P×(2x)4×P4(1−x)2×P2
Kp=8P3x5
Hence, option (A) is correct.