(i) PCI₅+ C₂H₅OH \(\longrightarrow \) C₂H₅CI + POCl₃ + HCI
(ii) P₄+ 10SO₂Cl₂ \(\longrightarrow \) 4PCI₅ + 10SO₂
(iii) POCl₃ + 3H₂O \(\longrightarrow \) H₃PO₄ + 3HCI
(iv) PH₃ + HBr\(\longrightarrow \) PH₄Br
(v) PCl₃+ 3H₂O\(\longrightarrow \) H₃PO₃ + 3 HCI

(i) In CIF₃, central atom CI has three bond pairs and two lone pairs.
(ii) According to VSEPR theory, the two lone pairs will occupy. The equatorial positions to minimise Ip-Ip and repulsions.
(iii) In addition, the axial fluorine atoms will be bent towards the equatorial fluorine in order to minimise the Ip-Ip repulsions.
(iv) Therefore CIF₃ has a bent T-shaped structure

(i) All these acids on losing a proton give their corresponding conjugate bases (ie) ClO-,
CIO₂ ^-, CIO₃ - and CIO₄ ^-. Their structures are:

(ii) Since, oxygen is more electronegative than chlorine, therefore dispersal of negative charge present on oxygen atom (Singly bonded to CI) increases as the number of oxygen atoms attached by a double bond: to chlorine increases due to \(P\pi -d\pi \) back bonding.
(iii) Therefore stability of ions will increase in the following order:
CIO- < CIO₂- < CIO₃- < CIO₄-
(iv) Due to increase in stability of conjugate bases, acidic strength of corresponding acid increases in the same order as :
HCIO- < HCIO₂ < HCIO₃ < HCIO₄

(i) The thermal stability of hydrides of group 16 elements is directly proportional to the bond dissociation enthalpy of H- E bond.
(ii) On moving down the group, bond dissociation energy decreases and hence, E- H bond breaks easily.
(iii) Thus, the thermal stability of hydrides of group 16 elements decreases down the group. Hence the order of thermal stability is,
H₂O > H₂S > H₂Se > H₂Te > H₂Po

(i) All halogens react with hydrogen to form volatile covalent hydrides of formula HX.
(ii) These hydrides are called hydracids.
(iii) Hydracids are the reducing agents.
(iv) Except HF, all hydrogen halides are gases. HF is a liquid because of intermolecular hydrogen bonding.
H-F...H-F....H-F....H-F
(v) The acidic character of HX are in the following order.
HF < HCI < HBr < HI.