Teachers Notes:

Problem 1:
Both the empirical and molecular formulas are CH₂O₂.

Problem 2:
1.00 μg CH₂O₂ x (0.000001 g/μg) x (1mole CH₂O₂/46.0256g CH₂O₂) x (6.02 x 1023 molecules/mole) = 1.31 x 1016 molecules CH₂O₂

Problem 3:
Both the empirical and molecular formulas are C₅H₁₁N.

Problem 4:
0.500mg C₅H₁₁N x (0.000001 g/mg) x (1mole C₅H₁₁N/85.14g C₅H₁₁N) x (6.02 x 1023 molecules/mole) = 3.54 x 1015 molecules C₅H₁₁N