Answer:
5.42 x 10²⁴
Explanation:
There is a number called Avogrado's constant, and this constant is:
6.022 x 10²³
The reason that this number is so important in chemistry calculations, is that it is the exact number of atoms in a mole of that substance.
Calculations:
No. of molecules = (Avogrado's constant) x n (where n is the moles)
No. of molecules = (6.022 x 10²³) x (9 moles)
No. of molecules = 5.42 x 10²⁴