Question
How many moles of magnesium phosphate, $$M{g_3}{\left( {P{O_4}} \right)_2}$$ will contain 0.25 mole of oxygen atoms?
A.
$$1.25 \times {10^{ - 2}}$$
B.
$$2.5 \times {10^{ - 2}}$$
C.
$$0.02$$
D.
$$3.125 \times {10^{ - 2}}$$
Answer :
$$3.125 \times {10^{ - 2}}$$
Solution :
$${\text{1}}\,Mole$$ of $$M{g_3}{\left( {P{O_4}} \right)_2}$$ contains $${\text{8}}\,\,mole$$ of oxygen atoms
$$\therefore \,\,8\,mole$$ of oxygen atoms $$ \equiv \,1\,mole$$ of $$M{g_3}{\left( {P{O_4}} \right)_{2\,}}mole$$ of $$M{g_3}{\left( {P{O_4}} \right)_2}$$
$$0.25\,mole$$ of oxygen atom $$ \equiv \frac{1}{8} \times 0.25\,mole$$ of $$M{g_3}{\left( {P{O_4}} \right)_2}$$
$$ = 3.125 \times {10^{ - 2}}\,mole$$ of $$M{g_3}{\left( {P{O_4}} \right)_2}$$