Among the following , the number of compounds that can react with `PCl_5` to give `POCl_3` is.
`O_2,CO_2,SO_2,H_2 O,H_2 SO_4,P_4 O_10`.

Answer

`(4)`

Explanation

(i) `PCl_5 + O_2 rarr "No reaction"`
(ii) `PCl_5 + CO_2 rarr "No reaction"`
(iii) `6 PCl_5 + P_4 O_10 rarr 10 POCl_3`
(iv) With limited amount of `H_2 O , PCl_5` gives `POCl_3` but with excess of water it does not give `POCl_3` but gives `H_3 PO_4`.
(a) `PCl_5 + H_2 O ("limited") rarr POCl_3 + 2 HCl`
(b) `PCl_5 + 4 H_2 O ("excess") rarr H_3 PO_4 + 5 HCl`
(v) `PCl_5 + SO_2 rarr SOCl_2 ("Thionyl chloride") + POCl_3`
(vi) `2 PCl_5 + H_2 SO_4 rarr underset (("Sulphuryl chloride")) (SO_2 Cl_2) + 2 POCl_3 + 2 HCl`.