0.125 mol
0.50 mol
0.333 mol
0.25 mol
Arsenic acid has a molar mass of 142 g/mol. 35.5 g of arsenic acid corresponds to 35.5/142 = 0.25 moles.
2H3AsO4 + 5H2S → As2S5 + 8H2O
The amount of arsenic pentasulfide that can be obtained is 0.25/2 = 0.125 mol
Hence, the correct option is 0.125 mol