0.93moles of Na
4.25 x 10⁻²³ moles of Cu
3.4 x 10²⁵atoms of Li
1.53 x 10²⁵ atoms of oxygen
5.48kg
Explanation:
1. How many moles are in 5.6 x 10 23 atoms of Na?
Problem 1:
Given parameters:
Number of atoms of Na = 5.6 x 10²³ atoms
Unknown:
Number of moles of Na = ?
Solution:
To solve this problem, we are going to adopt the mole concept. A mole of a substance is defined as the amount of a substance that contains the avogadro's number of particles.
Avogadro's number of particles = 6.02 x 10²³
Particles = atoms, molecules, formula units, protons, neutrons, electrons
6.02 x 10²³ atoms of Na = 1 mole
5.6 x 10²³ atoms of Na = 
= 0.93moles
2. How many moles are in 25.6 atoms of Cu?
Given parameters:
Number of atoms of Cu = 25.6 atoms
Unknown;
Number of moles = ?
Solution:
The mole concept also works in this case since we know that;
1 mole of substance = 6.02 x 10²³ atoms
x mole of Cu = 25.6 atoms;
Number of moles of Cu = 
= 4.25 x 10⁻²³ moles
3. How many atoms are in 56.5 moles of Li?
Given parameters:
Number of moles of Li = 56.5 moles
Unknown;
Number of atoms of Li = ?
Solution:
Since we have been given the number of moles, we can find the amount of atoms contained in this mole of Lithium.
We must understand that a mole of any substance contains the avogadro's number of particles.
1 mole of a substance = 6.02 x 10²³ atoms
56.5 mole of Li = 56.5 moles x 6.02 x 10²³ atoms = 3.4 x 10²⁵atoms
4. How many atoms are in 25.5 moles of oxygen? (O2)
Given parameters:
Number of moles given = 25.5 moles of Oxygen
Unknown:
Number of atoms = ?
Solution;
To find the number of atoms in a substance;
Number of atoms = number of moles x 6.02 x 10²³
This is because 1 mole of any substance contains 6.02 x 10²³ particles.
Substitute for the number of moles in the equation;
Number of atoms = 25.5 x 6.02 x 10²³ = 1.53 x 10²⁵ atoms of oxygen
5. How many grams of magnesium are in 225.6 moles of magnesium?
Given parameters:
Number of moles of Mg = 225.6moles
Unknown:
Mass of Mg = ?
Solution:
We are still going to use the mole concept to solve this problem. A mole of substance can also be related to the mass any element or compound;
Number of moles = 
Mass = number of moles x molar mass
From the periodic table, the molar mass of Mg = 24.3g/mol
Mass = 225.6 x 24.3 = 5482.08g = 5.48kg
