Find the grams in 1.26x10^-4 mol of hc2h3o2

 All you have to do is take the number of moles you have a multiply by the molar mass. The number of moles is given. To find the molar mass, add the atomic weights that make up your molecule.

Four hydrogen = Four amu (4*1)
Two carbon = 24 amu (2*12)
Two Oxygen = 32 (2*16)

Summing these, we have a molar mass of 60 grams/mole.

Multiply this by the number of moles and we get:

60(g/mol) * 1.26*10^-4 mol = .00756 g.