Answer:
no of moles = (mass) ÷ molar mass
you get the molar mass from the periodic table
n = 20.0g ÷ ( 149.09 g/mol )
= 0.134 mol
number of formula units = number of moles × (6.022×10^23)
= 8.07×10^22 units
number of hydrogen atoms in (NH4)3 PO3 = 12 × number of formula units
= 9.68×10^23 hydrogen atoms
