What is meant by mole?

Mole:

• The amount of a substance that contains the same number of elementary particles(ions, molecules, or atoms) as the number of atoms present in $12\mathrm{g}$ carbon$\left({\mathrm{C}}^{12}\right)$ is called the mole.
• It represents the number of substances just like dozen represents the 12 quantities of any item.
• One mole of a substance contains $6.022\times {10}^{23}$ elementary entities.

Formula for finding no. of mole:

$\text{Number of moles=}\frac{\text{Mass of substance}\left(\text{g}\right)}{\text{Molar mass}}$

Example:

• 12g of$\mathrm{C}$ contains exactly $6.022\times {10}^{23}$ carbon atoms.
• 2 g of Hydrogen gas contains exactly $6.022\times {10}^{23}$ of ${\mathrm{H}}_2$ molecules in it.