How many atoms are in 2.54 mole O?

 1.505 * 10^24 atoms

Work Shown:

1 mole = 6.02 * 10^23 atoms

2.5*(1 mole) = 2.5*(6.02 * 10^23 atoms)

2.5 moles = (2.5*6.02) * 10^23 atoms

2.5 moles = (15.05) * 10^23 atoms

2.5 moles = (1.505 * 10^1) * 10^23 atoms

2.5 moles = 1.505 * (10^1*10^23) atoms

2.5 moles = 1.505 * 10^(1+23) atoms

2.5 moles = 1.505 * 10^24 atoms

This is true for any element. This value is an approximation since there are roughly 6.02 * 10^23 atoms in 1 mole of any element.

the answer is definitely c.