Question

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

(A) 0.02 

(B) 3.125 x 10^-2 

(C) 1.25 x 10^-2 

(D) 2.5 x 10^-2

Answer 1

Correct option: (B) 3.125 x 10^-2 

1 mole of Mg₃(PO₄)₂ gives 8 moles of O₂

x moles will give 0.25 moles of O₂

x = \(\cfrac{0.25}{8}\) = 3.125 x 10^-2 moles.