Answer:
D = 5.27 g
Step-by-step explanation:
The molar mass of Li2SO4 is 2·7 + 32 + 64 = 110
18 g Li2SO4 contains 18/110 = 0.1636 mole Li2SO4, or 0.32727 mol Li
This allows to prepare 0.1091 mol Li3P
1 mole Li3P weighs 3·7 + 31 = 52 g/mol
0.1091 mol Li3P weighs 52 g · 0.1091 = 5.27 g