Answer
(a) $472.08$ $u$
(b) 88.10 $u$
(c) 120.91 $u$
Work Step by Step
(a) Molecular weight ($Hg_2Cl_2$):
200.59* 2 + 35.45* 2 = 472.08 $u$
(b) Molecular weight ($C_4H_8O_2$):
12.01* 4 + 1.008* 8 + 16.00* 2 = 88.10 g/mol
(c) Molecular weight ($CF_2Cl_2$):
12.01* 1 + 19.00* 2 + 35.45* 2 = 120.91 g/mol
