There are 5.43 x 10²³ present in 187 grams of XeF₄
Further explanation
The mole is the number of particles(molecules, atoms, ions) contained in a substance
1 mol = 6.02.10²³ particles
Can be formulated
N=n x No
N = number of particles
n = mol
No = Avogadro's = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass

mass of XeF₄ = 187 g
mol XeF₄ (MW=207,2836 g/mol) :

Number of molecules :
