Question

How many moles of magnesium phosphate, $Mg_{3} \left(po_{4}\right)_{2}$ will contain 0.25 mole of oxygen atoms ?

• A. 0.02
• B. $3.125\times10^{-2}$
• C. $1.25\times10^{-2}$
• D. $2.5\times10^{-2}$

Answer 1

Answer: (B)

$M g_{3} \left(po_{4}\right)_{2} ; mole$
8 moles of O-atom are contained by 1 mole
$M g_{3} \left(po_{4}\right)_{2\cdot} $
Hence, 0.25 moles of O-atom=$\frac{1}{8}\times0.25$
$=3.125\times10^{-2}$