Wny do we use the unit light years

Most objects in space are so far away, that using a relatively small unit of distance

45g of NaCl x 1mole of NaCl/58.5g

= 0.769moles of Nacl

Now Looking at the equation

1mole of Nacl produces 1mole of AgCl

so

0.769mole of NaCl will produces the same Mole of AgCl(0.769)

So the Moles of AgCl produced = 0.769

Recall

Mole = Mass /Molar Mass

Mass = Mole x Molar Mass

Molar Mass of AgCl =108 + 35.5 = 143.5

Mass of Agcl = 0.769 x 143.5

=110.35g of AgCl