What is the mass, in grams, of a sample of 7.83 x 10^24 atoms of helium (he)? show your work or explain thr steps that you used to determine your answer.

An important information, specifically a constant, we need to know is the Avogadro's number. Avogadro's number is equal to 6.022*10^23 mol^-1. 
This is the constant we use to convert atoms to moles. So we need to divide 7.83 x 10^24 atoms with the Avogadro's number to get the number of moles. That will be equal to 13 moles of He. Then to convert  moles to grams we need the molar mass of Helium (4 grams/mole). We then multiply the number of moles with the molar mass of Helium. We would have 52 grams of Helium. 

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.