To find the mass of Zn(OH)2, we first need to determine the amount of ZnSO4 in the given mass of the compound.

Mass of ZnSO4 = 1610 g * 20% = 322 g

Since the molar mass of ZnSO4 is 161.47 g/mol and Zn(OH)2 is 99.43 g/mol, we can set up a proportion to find the mass of Zn(OH)2:

322 g ZnSO4 = x g Zn(OH)2
161.47 g/mol ZnSO4 = 99.43 g/mol Zn(OH)2

x = (322 g * 99.43 g/mol) / 161.47 g/mol
x = 199 g

Therefore, the mass of Zn(OH)2 in the compound is 199 g.