All six possible diatomic compounds between F, Cl, Br and I are known. Indeed, ICl was first made independently by J. L. Gay Lussac and H. Davy in 1813, soon after the isolation of the parent halogens themselves, and its existence led J. von Liebig to miss the discovery of the new element bromine, which has similar properties. CIF is extremely robust; ICl and IBr are moderately stable and can be obtained in very pure crystalline form at room temperature; BrCl readily dissociates reversibly into its elements; BrF and IF disproportionate rapidly and irreversibly to a higher fluoride and Br₂ (or I₂). Hence, ClF is most stable compound at ambient temperature.

1) All the valence electrons in interhalogen compounds are present as bonding electron pairs (i.e. lone pairs), so these are diamagnetic in nature. 2) The diatomic interhalogen compounds undergo addition reaction through olefinic double bond sites to form addition products. 3) BrF₃ and IF₇ have been reported so far as fluorinating agents. Hence, the statements 1 and 3 both are incorrect.

Alumina trihydrate and octabromobiphenyl oxide are used as flame retardants for polymers.

ClF₃ (cololourless) and BrF₃ (yellow green liquid) are used as non aqueous solvents. These are used for the production of UF₆ in the enrichment of ²³⁵U.

A) Chlorine monofluoride (ClF) is the lightest interhalogen compound. ClF is a colourless gas with a normal boiling point of −100 °C. B) Iodine trichloride (ICl₃) forms lemon orange crystals, which can be melted under pressure to a brown liquid. It can be made from the elements at low temperature, or from iodine pentoxide and hydrogen chloride. It reacts with many metal chlorides to form tetrachloroiodides, and hydrolyses in water. The molecule is a planar dimer (ICl₃)₂, with each iodine atom surrounded by four chlorine atoms. C) Iodine monofluoride (IF) is very unstable gas and detected only by spectroscopically. It decomposes at 0 °C, disproportionating into elemental iodine and iodine pentafluoride. β-form of ICl is brown red crystalline solid. Hence, only statement C is false.

Poly methyl methacrylate (PMMA) is produced by the homopolymerisation of methyl methacrylate. PMMA is a transparent thermoplastic and used as a glass substitute. Hence, only polymer S is used as a glass substitute.

1. Bromine pentafluoride (BrF₅) is a colourless fuming liquid, made by reacting bromine trifluoride with fluorine at 200 °C. It is physically stable, but reacts violently with water and most metals and non-metals. It does not react with glass.
   1. Iodine trifluoride (IF₃) is a yellow powder, which decomposes above −28 °C.
   2. Iodine pentafluoride (IF₅) is a colourless liquid, made by reacting iodine pentoxide with fluorine, or iodine with silver(II) fluoride. It is highly reactive, even slowly with glass. It reacts with elements, oxides and carbon halides. The molecule has the form of a tetragonal pyramid. Hence, the statements 1, 2 and 3 all are true.

A large number of polymer applications in different fields depend on their unique mechanical properties like tensile strength, elasticity, toughness, etc. These mechanical properties are governed by intermolecular forces, e.g., van der Waals forces and hydrogen bonds, present in the polymer. These forces also bind the polymer chains. Under this category, the polymers are classified into the following four sub groups on the basis of magnitude of intermolecular forces present in them- elastomers, fibers, thermoplastic and thermosetting. Elastomers are rubber – like solids with elastic properties. In these elastomeric polymers, the polymer chains are held together by the weakest intermolecular forces. These weak binding forces permit the polymer to be stretched. A few ‘crosslinks’ are introduced in between the chains, which help the polymer to retract to its original position after the force is released as in vulcanised rubber. Examples are buna-S, buna-N, neoprene, Bromo Isobutylene Isoprene (bromobutyl), Viton (a brand of synthetic rubber and fluoropolymer elastomer commonly used in O-rings and other molded or extruded goods), etc.

Tricresyl phosphate and dipropyleneglycol benzoate are used as PVC plasticisers.

IBr is black crystalline solid with linear shape. ClF₅ is a colourless liquid with square pyramidal geometry. IF₇ is colourless gas with pentagonal bipyramidal shape. ICl₃ is orange crystalline solid with bent shape. Hence, the correct answer  is P-2-i, Q-3-iv, R-4-iii, S-1-ii.

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The best known brand name of PTFE is Teflon. Polyvinylidene difluoride (PVDF) is a highly non-reactive and pure thermoplastic fluoropolymer produced by the polymerisation of vinylidene difluoride. PVDF is sold under a variety of brand names including Hylar (Solvay), Kynar (Arkema) and Solef (Solvay). Poly ethylene oxide (PEO) is form from the polymerisation of ethylene oxide. The preparation of PEO is sold under the brand names Golytely, Gavilyte C, Nulytely, Glycolax, Fortrans, etc. Mylar is the brand name of polyethylene terephthalate (PETP). Hence, the representation of codes A-2, B-1, C-4, D-3 is correct.

 IF₅  reacts with xenon halides, forming adducts XeF₂.2IF₅ and XeF₄.IF₅. Hence, only the statement P is false.

2-hydroxybenzophenone is used as UV stabiliser for polymers. 2-mercaptobenzothiazole is used as accelerator in vulcanisation. Quinophthalone (greenish yellow) is used as colorant in vinyls and polyolefins. Dibromoneopentyl glycol (DBNPG) is a brominated flame retardant commonly used as additives during the manufacture of plastic polymers.

At room temperature (25 ^oC) ClF is colourless gas, BrCl is red brown gas, IBr is black crystalline solid and ICl is ruby red crystalline solid in physical state. Hence, the representation of codes A-2, B-1, C-4, D-3 is correct.

Polyvinyl butyral (PVB) is a resin usually used for applications that require strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility. It is prepared from polyvinyl alcohol by reaction with butyraldehyde. The major application is in the making of laminated safety glass for automobile windshields. Orlon is a addition polymer of acrylonitrile which is used for making clothes and fabrics like sweaters, hats, yarns, rugs, etc. Bakelite is the condensation polymer (copolymer) of phenol and formaldehyde. Bakelite is high electric, heat and chemical resistance polymer and used in the manufacturing of insulation of wires, manufacturing sockets, electrical devices, brake pads, etc. Twaron is the brandname of Teijin Aramid for a para-aramid. It is a heat-resistant and strong synthetic fibre developed in the early 1970s by the Dutch company AKZO. Twaron is a p-phenylene terephthalamide (PpPTA), the simplest form of the AABB para polyaramide. It is used in the making of bullet-proof body armour, helmets, brake pads, ropes, etc. Hence, the correct answer using the codes is P-2-i, Q-3-iv, R-4-iii, S-1-ii.