HELP If the molar mass of iodine is 131 g, how many nuclei are present in 4.0 x 10-11 g? (NA=6.02 x 1023).?

iodine is diatomic so it's chemical formula is I₂

From the periodic table the molar mass for I is 126.90 g/mol

BUT they give the molar mass as 131 g → so it looks like they mean atoms of some isotope of iodine

number of mol I atoms = 4.0 x 10⁻¹¹ g I atoms x [1 mol / 131 g] = 4.0 x 10⁻¹¹ / 131 mol I atoms

each mol I atoms = 6.02 x 10²³ atoms

each atom has one nucleus so:

number of I nuclei = (4.0 x 10⁻¹¹ / 131) mol I atoms x [6.02 x 10²³ nuclei / mol I atoms]

= 1.8 x 10¹¹ nuclei (to 2 sig figs)