How many atoms are there in 1.60 moles of selenium

There are 9.635 x 10^23 atoms in 1.6 moles of selenium

Explanation:

To solve this problem you have to use Avogadro´s constant (6.022 x 10^23).

In 1 mol of any element there are 6.022 x 10^23 atoms, so in 1.6 moles there will be...

1 mol Se 6.022 x 10^23 atoms

1.6 moles Se x = 9.635 x 10^23 atoms.