Which statement describes all chemical changes, but not all physical changes? Bubbles are produced. A new substance forms. Phase changes occur. A color change occurs.

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

Arollercoaster car at the top of a hill has potential energy kinetic energy chemical energy light energy

7. what temperature is need to just dissolve 50 g of nh4cl in 75 g of water? '