How many magnesium atoms are contained in 3.75 moles of magnesium?

In 1 mole of magnesium there are Avogadro's number of atoms are present.

Avogadro's number = 6.023 x 10²³

1 mole = 6.023 x 10²³ atoms

3.75 moles = 3.75 x 6.023 x 10²³

=2.26 x 10²⁴

So, in 3.75 moles of magnesium there are 2.26 x 10²⁴ atoms of magnesium are present.