Question

How many moles of magnesium phosphate, $M{g}_3(P{O}_4{)}_2$ will contain 0.25 mole of oxygen atoms ?

• A. $0.02$
• B. $3.125\times {10}^{-2}$
• C. $1.25\times {10}^{-2}$
• D. $2.5\times {10}^{-2}$

Answer 1

The correct option is B $3.125\times {10}^{-2}$

$1$ molecule of $M{g}_3(P{O}_4{)}_2$ has $8$ atoms of Oxygen.

$\Rightarrow 1$ mole of $M{g}_3(P{O}_4{)}_2$ has $8$ mole of Oxygen atoms.

Now, it is given $0.25$ mole of oxygen atoms

$\therefore$ Moles of $M{g}_3(P{O}_4{)}_2$ having $0.25$ mole of $O$ atoms is $\frac{0.25\times 1}{8}$ moles

$=0.03125$ moles

$=3.125\times {10}^{-2}$ moles

Hence, option B is correct.