4.5 moles Li (6.022 X 10^23/1 mole Li) = 2.7 X 10^24 atoms of lithium
2.5 moles Li × (6.02 ×1023 atoms) = 1.5 × 1024 atoms Li
No moles of BaCO3 are found in any amount of Li.
Subtract number of protons (=atomic number) 3 from the total number of protons AND neutrons ( p+n = mass number) 7, leaves the number of neutrons 4 7-3=4
It's 6.022 x 1023.