[jarutko]

I keep trying this problem and the place i submit my answers says its wrong.

A sample of S8(g) is placed in an otherwise empty rigid container at 1325 K at an initial pressure of 1.00 atm, where it decomposes to S2(g) by the following reaction.
S8(g)  4 S2(g)

At equilibrium, the partial pressure of S8 is 0.25 atm. Calculate Kp for this reaction at 1325 K.
What do you get? and how'd u figure this out. I appreciate any help.

[Yggdrasil]

Suppose your container is 1L.  Figure out how many moles of S₈ you have initially.  Then figure out how many moles of S₈ you have at equilibrium.