An atom has a mass number of 22 and an atomic number of 12. How many neutrons
does it have?

this isn't correct answer but the equation is correct by using this methid you can got your answer .

Explanation:

Given - Mass number of atom = 23

                                Atomic number of atom = 11

As, no. of electrons in an atom is equal to an atomic number of the element.

So, number of electrons = 11

Secondly , number of protons are equal to number of electrons.

so, number of protons = 11

And number of neutrons = mass number - atomic number = 23−11 = 12

so, number of neutrons = 12

So , the atom contains 11 protons, 11 electrons, 12 neutrons.

that's what i got you can count the number of atoms

i think its 100

i hope this !