How many electrons are in 7.00 g of 13c?

13C or C-13 is an isotope of the Carbon element. It has an atomic mass of 13 amu or 13 g/mol. So, we can convert the mass in terms of moles, then moles in terms of atoms using the Avogadro's number. For every 1 atom of C, there are 6 electrons.

7 g C (1 mol/13 g) (6.022*10²³ atoms/mol) (6 electrons/atom) = 1.946*10²⁴ electrons