Answer:
The mass is 9,36grams
Explanation:
We use the Avogadro´s Number:
1 mol contains 6, 023x10e23 particles
Weight 1 mol of He= 4, 002602 grams (value obtained from periodic table)
6, 02x10e23 particles------4, 002602 grams He
7.06 x 10e23 particles------x=
x=(7.06 x 10e23 particlesx4, 002602 grams He)/6, 02x10e23 particles
x=9, 357076199 grams He
