Question

How many moles of $N_2$ are there in 4.3 $\times$ $10^{22}$ $N_2$ molecules?

Answer 1

Hint: A mole is one of the fundamental units which helps to calculate a big number. In any chemical reaction, the number of mole ratio of reactant and product is always fixed i.e., we always use a fixed number of molecules of reactant to form a fixed number of moles of product.

Complete step by step answer:
A mole is derived from a greek word called mol. which means a heap or pile. It is used to calculate a big number which is difficult to calculate in real numbers.
In the international system of units called SI system, mole is one of the fundamental units which help us to calculate the big numbers.
It is also called wogadron number in respect of Amedeo Avogadro and one mole of any substance (atoms, ions, molecules, electron neutron and proton) is equal to
$1$ mole $=6.022\times {{10}^{23}}$ particles.
In chemistry, mole is widely used to calculate the amount of substance formed, volume of gas released at standard temperature and pressure condition called STP, number of particles or molecules formed during a chemical reaction.
It also helps us to calculate the gram molecular mass and gram atomic mass of a substance.
In this question we have to find the number of moles in $4.3\times {{10}^{23}}$ of ${{\text{N}}_{2}}$ molecules.
One mole of atom contains NA number of atoms
Where $N_A$ $=6.022\times {{10}^{23}}$ mol$^{-1}$
No of molecule $=$ Given mol $\times $ Avogadro's numbers
$4.3\times {{10}^{23}}=$ mole $\times \,6.022\times {{10}^{23}}$
$\dfrac{4.3\times {{10}^{23}}}{6.022\times {{10}^{23}}}=$ mole of ${{\text{N}}_{2}}$
$0.71=$ moles of ${{N}_{2}}$
Final Answer: Here from the formula we have get the number of moles of ${{\text{N}}_{\text{2}}}$ i.e. $0.71$ moles of ${{\text{N}}_{2}}$ .

Note: Mole can also be find out by many ways
Number of moles = $\dfrac{mass \;of\; given\; atom }{ gram \;atomic\; mass }$
Number of moles =$\dfrac{ mass\; of \;given\; molecule}{gram\; molecular\; mass}$
Number of moles = $\dfrac{Given\; volume\; of\; gas\; at\; STP }{molar\; volume \;of \;22.4Liter}$