Is plastic is substance, homogenous or heterogineous mixture

How much heat is released upon converting one mole of steam (18.0 g) from 100.0 ∘c to water at 25.0 ∘c? show work and constants, trying to figure out how it works. only given the heat capacity for steam and water so try to only use that

In numbering carbon atoms in the parent chain of a hydrocarbon, why would you number from right to left, rather than left to right

What is the relationship of air masses and the temperature of oceans?