(a) Account for the following observations :
(i) `SF_(1)` is easily hydrolysed whereas `SF_(6)` is not easily hydrolysed.
(ii) Chlorine water is a powerful bleaching agent.
(iii) Bi (V) is a stronger oxidising agent than Sb(V)
(b) What happens when :
(i) White phosphorus is heated with concentrated NaOH solution in an inert atmosphere of `CO_(2).`
(ii) `XeF_(6)` undergoes partial hydrolysis.
(Give the chemical equations involved).

Explanation

(a) (i) S atom in `SF_(4)` is not sterically protected as it is surrounded by only four F atoms, so attack of water molecules can take place easily. In contrast, S atom in `SF_(6)` is protected by six F atoms. Thus attack by water molecules cannot take place easily.
(ii) Chlorine water produces nascent oxygen (causes oxidation) which is responsible for bleaching action.
`CH_(2) + H_(2)O to 2HCI + [O]`
(iii) Due to inert pair affect Bi(V) can accept a pair of electrons to form more stable Bi (III). (+ 3 oxidation state of Bi is more stable than its + 5 oxidation state).
(b) (i) Phosphorus undergoes disproportionation reaction to form phosphine gas.
`P_(4) + 3NaOH + 3H_(2)O to PH_(3) + 3NaH_(2) PO_(2)`
(ii) On partial hydrolysis `XeF_(6)` gives oxyfluoride `XeOF_(4)` and HF.
`XeF_(6) + H_(2)O to XeOF_(4) + 2HF`