A sample of 7.83*10^24 atoms of heliums in grams would equal out to 52 grams.
How?
To do this, we need to use the Avogadro's law/number. His number would equal out to 6.022*10^23 molecules^-1.
Next, we divide 7.83 x 10^24 atoms with Avogadro's number to get the number of molecules.
7.83 x 10^24 ÷ 6.022*10^23 = 13 molecules of (He). Now, to convert it to grams, we need the molar mass of helium.
Multiply the number of molecules with the molar mass of grams, then we would end up with 52 grams of helium.