The oxidation number of nitrogen in NCl3 is

'N' and 'Cl' have same value of EN on pauling scale (EN=3) Nitrogen is smaller than chlorine its oxidation state in NCl3 must be negativeNCl3x + 3(+1) = 0x = -3EvidenceNCl3 + 3H2O → NH3 + 3HOClThe product clearly indicate that the -ve pole nitrogen goes with positive pole of water (H+)