Question

How many ions are in the 20 grams of magnesium oxide

Answer 1

Answer:

$\frac{1}{2} \: mole \: of \: MgO \: in \: 1 \: mole \: of \: ions$

Answer 2

Answer:

1/2 mole of MgO in 1 mole of ions.

Explanation:

Compare your question to this one:

How many wheels in 1/2 dozen bicycles?

Since each bicycle has 2 wheels there will be 1 dozen wheels.

Just like bicycles, each MgO formula has two ions, Mg2+ and O2-, so there will be twice as many ions as formula units.

If there is 1/2 mole of MgO, there will be 1mole of ions.