Which particle diagram represents a sample of matter that can not be broken down by chemical means?

Agas mixture with a total pressure of 745 mmhg contains each of the following gases at the indicated partial pressures: co2, 245 mmhg ; ar, 119 mmhg ; and o2, 163 mmhg . the mixture also contains helium gas. part a what is the partial pressure of the helium gas? phe p h e = nothing mmhg request answer part b what mass of helium gas is present in a 10.2-l sample of this mixture at 283 k ? m m = nothing g request answer

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

There are main groups in the modern periodic table of elements