Bond energy of `N-H,H-H` and `N-=N` are `a,b,c` respectively. The `DeltaH` for the reaction,
`2NH_(3) rarr N_(2)+3H_(2)` is `:`

Answer

3

Explanation

three compounds are optically active. These are:
amine: `CH_(3)CH_(2)overset(**)(C)H(CH_(3))N(CH_(3))C_(2)H_(5)`,
quaternary ammonium salt:
` [Ph(CH_(3))(C_(2)H_(5))overset(+)(N)H]I^(-) and ` amide N-oxide: `C_(6)H_(5)(CH_(3))(C_(2)H_(5))overset(+)(N)-O^(-)`.