Option (b) is the correct answer.
It is given that mass of Mg is 97.22 g and it is known that molar mass of Mg is 24.305 g/mol.
So, calculate the number of moles as follows.
No. of moles =
= 4 mol
Also, it is known that 1 mole has atoms/mol. Therefore, calculate the number of atoms in 4 mol as follows.
or, = atoms
Thus, we can conclude that there are atoms in 97.22 grams of Mg.
Number of atoms = Number of moles x Avogadro's Number
So first we need to find the number of moles in 97.22 grams of Mg.
Atomic Mass of Mg = 24
Number of moles = n = Given Mass / Atomic Mass
n = 97.22/24 = 4.05
Now we can calculate the Number of Mg atoms in 97.22 .
Number of atoms =