The amount of arsenic pentasulhide that can be obtained when `35.5g` arsenic acid is treated with axess `H_(2)S` in the presence of conc. `HCl` `("assuming" 100% "conversion")` is :

Options

A. 0.25 mol
B. 0.50 mol
C. 0.333 mol
D. 0.125 mol

Answer

D

Explanation

`underset(underset("1 mole")("2moles"))(2H_(3)AsO_(4))+5H_(2)S overset("Conc. HCl")to underset(underset(1 // 4 "mole")("1 mole"))(As_(2)S_(5))+8H_(2)O`
`:.` number of moles of `H_(3)AsO_(4)=(35.5)/(142)=0.25`
`:.` number of moles of `As_(2)S_(5)=(0.25)/(2)=0.125 mol.`