Among `NH_(3), HNO_(3), N_(2)` and `Mg_(3)N_(2)` , the number of molecules having nitrogen in negative oxidation state is :

Answer

3

Explanation

Calculating the oxidation state of nitrogen in given molecules,
Oxidation state of N in `NH_(3)` is
`x + 3 xx (+1) =0` or `x=-3`
Oxidation state on N in `NaNO_(3)` is
`1+x+3 xx (-2) =0` or `x=+5`
Oxidation state of N in `NaN_(3)` is
`x=-1/3`
Oxidation state of N in `Mg_(3)N_(2)` is
`=3 xx 2 + 2x =0` or `x=-3`
Thus, 3 molecules (i.e. `NH_(3), NaN_(3)` and `Mg_(3)N_(2)`, have nitrogen in negative oxidation state.