Question

The total number of valence electrons in 4.2 g of N^-3 ion is (NA is the Avogadro's number)

Answer 1

No.of ions in 0.3 moles is 0.3*N no of nitride ions. Nitride ion is a stable ion, meaning it has 8 valence electrons. The no of moles of nitride ion in 4.2g is 4.2/14=0.3 mol. So the no of valence electrons is equal to 8x0.3xNa, where Na is avogadros no. whose value is (6.022x10^23).

Answer 2

42g of N3-contains no of e-= 16

4.2g contains=16x4.2/42

=1.6 valence electrons