How many atoms are in 49.6 g Se?

3.79 ×10²³ atoms

Explanation:

Given data:

Mass of Se = 49.6 g

Number of atoms = ?

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass of selenium is 78.96 g/mol.

by putting values,

Number of  moles = 49.6 g/ 78.96 g/mol.

Number of moles = 0.63 mol

Number of atoms:

Now we will apply Avogadro number.

1 mole contain 6.022×10²³ atoms

0.63 mol ×  6.022×10²³ atoms / 1 mol

3.79 ×10²³ atoms

yes the answer is total mass in unchanged   : )