Question

Define mole?

Answer 1

Often problem arises to measure the substances which are very much small in size and is difficult to count so to combat with this problem , a new term ‘mole’ was designed to count the small particles like electrons, protons , atoms , molecules.

Complete answer:
So, mole is the SI base unit to measure the amount of substances be it atoms, molecules or protons or electrons.
Mole is a term dedicated to measure the amount of substance or measure the number of electrons, protons, atoms and molecules of some chemical unit.
So, we can now know the value of one mole of a substance. Generally $1$ moll is equal to the Avogadro’s number. Value of Avogadro’s number is (NA) $= 6.022 \times {10^{23}}$ .
Also the symbol ‘mol’ is defined in the form of the amount of substance that comprises of as many molecules, atoms, electrons or ions of any elementary entity as the number of carbon atoms in twelve grams of carbon atoms present in the $12$ grams of the $12$C isotopes. So, it is the number of atoms in the twelve gram of the $12$C isotope. And it is called Avogadro’s number.

Note:
The mole concept idea was given by ‘Amadeo Avogadro’. Originally he proposed that the amount of gas present at a particular temperature and pressure is directly proportional to the number of ions, molecules or atoms. So, by ‘Amadeo Avogadro’ did not propose the term ‘mole’. But it was his core idea that lead to the development of the mole concept relating the amount of gas with the particles present in them.