What is The relationship of the mole and how to calculate the number of atoms and molecules using the mole concept?

Answer 1

The mole and the number of atoms and/or molecules are related via Avogadro's number, which is 6.02x10²³.

There are 6.02x10²³ "particles" in 1 mole of anything. So, there are 6.02x10²³ Na atoms in a mole of Na; 6.02x10²³ H₂O molecules in a mole of water; 6.02x10²³ NaCl formula units in a mole of NaCl; and 6.02x10²³ bricks in a mole of bricks.