[maivu]

Draw dot-cross diagram of Ba₃N₂. This compound is known as Barium nitride not Barium nitrate.

I've been trying to work it out but none of them was accepted.

[maivu]

Finally, I've got the answer for this question. Ba₃N₂ is an ionic compound. The ionic compound contains 3 Ba²⁺ cations and 2 N^3- anions. Since it's ionic compound, there will be completely transfer of electrons from less electronegative atom to more electronegative atom.

[Ba]²⁺
[Ba]²⁺    [N]^3-
[Ba]²⁺    [N]^3-

Each Ba has lost 2 electrons in its outermost shell to form Ba²⁺. Three Ba have lost totally 6 electrons. These 6 electrons will move to Nitrogen to form N^3-

Each Nitrogen will receive 3 electrons from Barium. Therefore, each Nitrogen is surrounded by 8 electrons, 5 of them belong to Nitrogen itself and the other 3 of them belong to Barium.