5) 0.028 g of (NH4)2SO4
= ? moles N

0.0002118973 moles

Explanation:  https://www.webqc.org/molecular-weight-of-%28NH4%292SO4.html

i think   the answer is c hope i'm right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer