Solution —
We know that 1 mole of atoms contains 6.022 x 1023 atoms.
Now,
1 mole of sodium atoms = 6.022 x 1023 atoms. So,
0.2 mole of sodium atoms = 6.022 x 1023 x 0.2 atoms
= 12.044 x 1022 atoms
Thus, 0.2 mole of Sodium element has 12.044 × 1022 Atoms in it.