How many O atoms are present in 2.0 moles of Na3PO4?

Find out how many molecules there are in 2moles

To do this multiply avagadro's constant by 2 (6.02x10^23 * 2)

This gives 1.204x10^24 molecules

For every molecule you have 4 oxygen atoms so do 1.204x10^24 * 4

Answer = 4.816x10^24