Equivalent weight of ${\mathrm{NH}}_3$in the change

${\mathrm{N}}_2⟶{\mathrm{NH}}_3$

Molecular weight of NH 3 =17g

Oxidation number of nitrogen in ${\mathrm{N}}_2=0$

Oxidation no. of N in ${\mathrm{NH}}_3$ = -3

We already know that 

eq. weight = mole weight / valence factor. 

NH3 equivalent weight for the specified change Consequently, the equivalent weight of NH with the specified change $=\frac{17}{3}$ shall be

Equivalent weight of $N{H}_3$  in the change  $N_2⟶N{H}_3$ is : 17/3