The molecular weight of calcium carbonate, caco3, is 100.09 3.
mol
how many moles of calcium carbonate are in 63.8 g of calcium carbonate?
express the answer using 3 significant figures.

Number of Moles = Reacting mass / Molecular mass

                              = 63.8 / 100.09

                              = 0.637g

Hence, the moles of calcium carbonate  in 63.8 g of calcium carbonate is 0.637g

Explanation:

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

i think its 100.

hope this !