The Brainliest Answer!
Mole  is  the  unit  used   to  express  atoms,molecules  and  ions.6.022×10²³   number  of  atoms,molecules  or  ions  is  called  1  mole.

eg  1  mole  carbon  atom  =  6.022×10²³  carbon  atoms or  12  grams
      1  mole  hydrogen  atom=6.022×10²³ hydrogen  atom  or  1  gram

Number  of  moles  =  Given mass/Molar  mass

n=  number  of   moles 
W =  Given  mass
 M = molar  mass
N = Number   of  particles   
No=  Avogardo  number 

-  n=N/M  or  n  = N/No
-  W =M×N/No

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Also one mole of a gas at STP occupies 22.4 litres of volume.
The number of particles(atoms, molecules or ions) present in one mole of any substance is fixed with a value of 6.022 x 10 to the power of 23. this is an experimentally obtained value and is called the avogadro constant.
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