Determine the numbers of atoms in each of the following:

5.40g b
0.250 mol k
0.0384 mol k
0.02550g pt
1.00 x 10^-10g au

The number of atoms found in each element is equal to Avogadro's number which is equal to 6.022 x 1023 atoms per mole element.
1. 5.40 gram of Boron is equal to 3x 1023 atoms2.  1.5055 x 1023 atoms K3.  2.31 x 1022 atoms K4. 7.72 x1019 atoms Pt5. 3.06 x1011 atoms Au

The molar mass of a substance is defined as the mass of 1 mol of that substance, expressed in grams per mole, and is equal to the mass of 6.022 × 10 23 atoms, molecules, or formula units of that substance.