There are 8.786 g
Further explanation
The mole is the number of particles contained in a substance
1 mol = 6.02.10²³
2.30 x 10²³ atoms in Na :
[tex]\tt mol=\dfrac{2.3\times 10^{23}}{6.02\times 10^{23}}=0.382[/tex]
mass :
[tex]\tt mass=mol\times Ar~Na\\\\mass=0.382\times 23=8.786~g[/tex]
