With the help of `F.C`. Explain which Lewis structure is more stable for the following molecules :
(a) `N_(2)O: (i) :^(Theta)ddotN =overset(2+)O=ddotN:^(Theta) or (ii) :N -=overset(o+)N-ddotunderset(..)O:^(Theta)`
(b). `H_(2)SO_(4): (i) H-O-overset( :ddotO:^(Theta))overset(|)underset(Theta)underset( :underset(..)O: )underset(|)(S^(+2))-O-H or (ii) H-O-underset( underset(..):O)underset(||)overset(ddotO: )overset(||)S-O-H`
`HNO_(3)(i) H-O-underset(Theta)underset( :underset(..)O: )underset(|)overset(o+)N=ddotO: or (ii) H-O-underset(underset(..):O:_(Theta))underset(|)overset(+2)N-underset(..)ddotO:^(Theta)`
(d). `CI_(2)O: (i) underset(..):ddotCI-ddotunderset(..)O-underset(..)ddotCI: or (ii) :underset(..)ddotO-underset(..)ddot(CI)-underset(..)ddotCI:`

Explanation

(a) Structure (ii) is more stable, as it has less `F.C`. The central `N` has an `F.C` of `+ 1` and `O` has an `F.C` of `-1` But in structure (i), both `N` atoms have `F.C` of `- 1` and `O` has `F.C` of `+2`.
(b) Structure (ii) is more stable, as it has no `F.C`, whereas structure (i) has `F.C` of `+2` on `S` and `F.C` of `-1` on each `O`.
`S` has `d` orbitals, so it can expand its octet to have more than eight `overline e^, s`.
( c) Structure (i) is more stable, as it has less `F.C`. than structure (ii). Moreover, structure (ii) is not possible, because `N` has no `d` orbitals, so it cannot expand its octet and is limited to an octet.
(d) Structure (i) is more stable, as it has no `F.C`., whereas structure (ii) has `F.C`. of `-1` on `O` and of `+ 1` on central `C 1`.
`F.C`, in (i) : `F.C` on each `C 1= [7 - 6 - (1)/(2) (2)] = 0`
`F.C on O = [6 - 4 - (1)/(2)(4)] = 0`
`F.C` in (ii) `F.C` on `O = [6 - 6 - (1)/(2)(2)] = -1`
`F.C` on central `C 1 = [7 - 4 - (1)/(2)(4)] = + 1`
`F.C` on terminal `C1 = [7-6- (1)/(2)(2)] = 0`.