Balance these chemical equations mg(s)_ + _N2(g) = _mg3N2

Explanation:

The valance of magnesium atom is  

While the valence of nitrogen atom is

Let us first write the first  half-reactions

The second half reaction is

Adding the above two reactions and writing the final reaction, we get -

The balance equation is

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock