How many moles of magnesium phosphate

How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mole of oxygen atoms?

  1. 2.5 x 10-2
  2. 0.02
  3. 1.25 x 10-2
  4. 3.125 x 10-2

Answer

1 mol of Mg3(PO4)2 = 3 mol of Mg atom + 2 mol of P atom + 8 mol of O atom

8 mol of oxygen atoms are present in = 1 mol of Mg3(PO4)2

0.25 mol of oxygen atoms are present in = 1 *.25/8= 3.125*10-2 mol of Mg3(PO4)2

The correct option is D.