Answer :

Molar mass :

HC₂H₃O₂ = 1 + 12*2 + 1 * 3 + 16 * 2 = 60 g/mol

1 mole HC₂H₃O₂ -------------- 60 g
1.26x10-⁴ mole ----------------- mass

mass =  1.26x10-⁴ * 60

mass = 0.00756 g of HC₂H₃O₂

hope this helps!