How much lead (pb) is in 5.07 * 1012 atoms of lead? answer in units of mol?

2.49⋅ 10 - 12 moles Pb

Explanation:

Before doing any calculations, it's worth noting that atoms do not contain moles, it's the other way around.

A mole is simply a collection of atoms. More specifically, you need to have exactly 6.022⋅ 1023 atoms of an element in order to have one mole of that element - this is known as Avogadro's number.

In your case, you must determine how many moles of lead would contain 1.50⋅ 1012 atoms of lead.

Well, if you know that one mole of lead must contain 6.022⋅ 1023 atoms of lead, it follows that you get 1.50⋅ 1012 atoms of lead in

1.50⋅ 1012 atoms of Pb⋅ 1 mole Pb 6.022⋅ 1023 atoms of Pb = 2.49⋅ 10 - 12 moles Pb