For this question we have to start with balanced chemical equation.
3CaCO3+ 2FePO4 --> Ca3(PO4)2 + Fe2(CO3)3 (a)
As per the above equation (a) Three moles of CaCO3 , consumes two moles of FePO4.
In terms of mass one mole of CaCO3 , has mass 100 g/mol.
and one mole of FePO4 has mass 150.8 g/mol.
so let us set up the ratio;
3 moleCaCO32 moleFePO4 = 300g301.6g (b)
X g of CaCO3 will consume 45 g of FePO4 (c)
equating two equation (b) and (c)
300g301.6g = Xg45g
300 x 45 = 301.6 X
301.6 X = 13500
X = 13500301.6 = 44.7 g => 45 g
So, 45 g of CaCO3 will react with 45 g of FePO4 . The amount of FePO4 added is 45 g. The amount of CaCO3 remains unused is 100-45= 55 g. Iron (III) phosphate is a limiting reagent.
2 moles of FePO4 produces 1 mole of Ca3(PO4)2
301.6 g of FePO4 produces 310.17 g Ca3(PO4)2 (d)
45 FePO4 produces X g Ca3(PO4)2 (e)
301.6g310.17g = 45gXg
301.6 ( X ) = 45 x 310.17
301.6 (X) = 13957.65
X = 13957.65301.6 = 46.27 g