Explanation:
We have to find the number of Ge atoms present in a sample that contains 4.20 moles of Ge. By definition we know that 1 mol of Ge atoms contains 6.022 *10^23 atoms of it. We can use that ratio to find the answer to our problem.
1 mol of Ge : 6.022 *10^23 atoms
number of atoms = 4.20 moles of Ge * 6.022 *10^23 atoms/(1 mol of Ge)
number of atoms = 2.53 *10^24 atoms
Answer: 2.53 *10^24 atoms of Ge are present in 4.20 moles of it.
