Step 1
Avogadros number is given by:
1 mol F2 = 38 g approx. = 6.02x10^23 fomula units (molecules in this case)
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Step 2
Procedure:
38 g of F2 --------- 6.02x10^23 molecules of F2
X --------- 3.10x10^24 molecules of F2
X = 3.10x10^24 molecules of F2 x 38 g F2/6.02x10^23 molecules of F2
X = 195.7 g approx.
Answer: 195.7 g F2