Answer : The mass of 12.3 moles of helium (He) is, 49.2 grams.
Solution : Given,
Moles of helium = 12.3 moles
Molar mass of helium = 4 g/mole
Formula used :
[tex]\text{Mass of helium}=\text{Moles of helium}\times \text{Molar mass of helium}[/tex]
[tex]\text{Mass of helium}=(12.3mole)\times (4g/mole)=49.2g[/tex]
Therefore, the mass of 12.3 moles of helium (He) is, 49.2 grams.
