Hm I’m confused, if you mean what are they weighting, it’s they :)
Both aluminum and chlorine have known charges, which are +3 and -1 respectively. To make them cancel each other out in charge, you would need 3 chlorine and for one aluminum, therefore

would be correct
It would be B, so yeah hope that helps ya ;)
Answer: 30.06% is your answer.
I hope this helps.
Stay safe and have a good day :D
Chemical reaction: 4PBr₃(g) → P₄(g) + 6Br₂<span>(g).
</span>Pressure equilibrium constant (Kp) express the relationship between product pressures and reactant pressures. The partial pressures of gases are used to calculate pressure equilibrium constant.
Kp = (p(P₄) · p(Br₂)⁶) ÷ p(PBr₃)⁴.
p(P₄) - partial pressure of phosphorus.
p(Br₂) - partial pressure of bromine.