Which two atoms could be the "before'' and ''after'' of an alpha ejection

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 many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

The diagram below shows the different phase transitions that occur in matter. which arrow represents the transition in which dew is formed?