During chemical reactions thermal energy is absorbed and/or released, whiles mass is gained or lost. (true or false question btw)

The electron configuration for chromium is 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 5 4 s 1 instead of 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 4 4 s 1 . the configuration is an exception to the

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

If you have 5.25 grams of methane (ch4), how many grams of co2 will you produce ?