State reaso

(i) In the resonance structure of these two species, in NO₂^-, 2 bonds are sharing a double bond while in NO₃^-, 3 bonds are sharing a double bond which means that bond in NO₂^- will be shorter than in NO₂^- or we can say that in NO₂^- bond order is 1.5 while in NO₂^- bond order is 1.33

(ii) SF₆ is kinetically inert due to high oxidizing power and electronegativity of fluorine atom which causes steric hindrance and it unable to react further with any other atom

OR

i) It is because PCl₅has a trigonal bipyramidal structure and all bonds are not in same plane. Three P-Cl equatorial bonds are in one plane whereas two axial bonds are in vertical plane which are longer than equatorial bonds

ii) Sulphur has a much greater tendency for catenation than oxygen because of its bigger size and low electronegativity due to which the S-S bond is stronger than O-O bond and there is more interelectronic repulsion in O-O than in S-S bond