how many atoms of Na are there in every 2.5g of Na? please answer me! thank you!
You need to calculate how many moles of Na you have and then use that each mole of any substance contains 6.02 x 10^23 particles (in this case atoms).
So number of moles of Na is
2.5 g /23 g mole^-1
hence calculate the number of atoms knowing that each mole contains
6.02x10^23 atoms.