To determine the number of atoms in 4.0 moles of boron, we can use Avogadro's number, which represents the number of entities (atoms, molecules, ions) present in one mole of a substance. Avogadro's number is approximately 6.022 x 10^23.

Using Avogadro's number, we can calculate the number of atoms in 4.0 moles of boron as follows:

Number of atoms = (Number of moles) x (Avogadro's number)

Number of atoms = (4.0 moles) x (6.022 x 10^23 atoms/mole)

Number of atoms = 2.4088 x 10^24 atoms

Therefore, there are approximately 2.4088 x 10^24 atoms in 4.0 moles of boron.