Answer
a) $C_2H_2$
b) $C_4H_4O_4$
c) $CH_2$, $112.21\ g/mol$
Work Step by Step
a) Empirical formula's molar mass: $M_u=13.02\ g/mol$
$M/M_u=2.0$, empirical formula: $CH$
Molecular formula: $C_2H_2$
b) Empirical formula's molar mass: $M_u=29.02\ g/mol$
$M/M_u=4.0$, empirical formula: $CHO$
Molecular formula: $C_4H_4O_4$
c) From the molecular formula: empirical formula $CH_2$ (8 units)
Molar mass: $112.21\ g/mol$
