Pleas answe ASAPPP

Help pleas is this an octane

1.explain the steady increase in the bonding points in the series CH4-PbH4 and which of those molecules would have the highest vapor pressure? the lowest? Briefly explain your answer? I'm trying to understand the question of my exam pleas explain it in the easiest way possible. thank you

2. SO2, He, HF, CaF2 Ar please list them in order of increasing normal boing point and pleas explain why. pleas make the explanation as easy as posible