N¨−N¨ single bond weaker than P¨−P¨ due to more ℓp−ℓp repulsion.
Bond length ⇒dp−p>dN−N(size↑, B.L. ↑)
In group 15 elements only N & P show disproportionation in +3 oxidation state, As, Sb & Bi have almost inert for disproportionation in +3 oxidation state.
So both statements are false.