(a) Explain the following :
(i) `NF_(3)` is an exothermic compound whereas `NCl_(3)` is not
(ii) `F_(2)` is most reactive of all the four common halogens.
(b) Complete the following chemical equations :
(i) `C+H_(2)SO_(4) (conc) to`
(ii) `P_(4)+NaOH+H_(2)Oto`
(iii) `underset("excess")(Cl_(2)+F_(2))to`

Explanation

(a) (i) See Q. 29 (b) (ii), Delhi Board, 2010.
(ii) Because of small size, highest eledtro negativity and low bond dissociation enthalp) of f-f bond, fluorine is most reactive.
(b) (i) `C+2H_2SO_4("conc".)to2SO_2+CO_2+2H_2O`
(ii) `P_4+3NaOH+3H_2Otounderset("Phosphine")(PH_3)+underset("Sodium hypaphosphite")(3NaH_2PO_2)`
(iii) `{:(C_2+3F_2overset("heat")to2ClF_3),(""" (excess)"):}`