Explain
(a )Which d-orbital in involved in
(i) `sp^(3)`d hybridisation (ii) `sp^(3) d^(2)` hybridisation
(iii) `dsp^(2)` hybridisation (iv) `sp^(3)d^(3)` hybridisation
(b) Why `H_(2)O` is liquid while `H_(2)S` is gas
(c ) Why `KHF_(2)` exists but `KHCI_(2)` does not
(d) Benzene ring contains alternate single and double bonds yet all the `C-C` bonds are of equal lenght why
(e) Out of `P-F,CI-F,S-F` and `F-F` bonds, which bond is the least ionic? .

Explanation

(i) `dz^(2)` (ii) `dx^(2) -y^(2)` and `dz^(2)`
(iii) `dx^(2)-y^(2)` (iv) `dxy,dyz,dxz`
(b) Due to intermolecular H-bonding in `H_(2)O` association of `H_(2)O` molecules occurs but in `H_(2)S` there is no H-bonding
(d) Due to resonance in benzene
(e) `F-F` is the least ionic or more covalent due to the zero `EN` difference in `F-F` atoms Greater the difference in `EN` value of two atoms more ionic is the compound and vice versa .