Match List I with List II

Choose the correct answers from the options given below:

A-III, B-I, C-IV, D-II

The correct answer is option 4. A-III, B-I, C-IV, D-II.

Let us go through each molecule step by step, analyzing the electronic structure, VSEPR (Valence Shell Electron Pair Repulsion) theory, and molecular geometry to explain the matching process.

A. \(PCl_3\) (Phosphorus Trichloride): III. Trigonal pyramidal

Phosphorus (P) has 5 valence electrons. Chlorine (Cl) has 7 valence electrons, and there are 3 chlorine atoms. Phosphorus forms three single bonds with chlorine atoms, using 3 of its 5 valence electrons. The remaining 2 valence electrons on phosphorus form a lone pair. There are 4 electron pairs (3 bonding pairs + 1 lone pair) around the phosphorus atom. According to VSEPR theory, the shape is determined by the arrangement of these electron pairs to minimize repulsion. The electron pairs arrange themselves in a tetrahedral geometry. However, the presence of a lone pair distorts this geometry, leading to a trigonal pyramidal shape for \(PCl_3\).

B. \(SF_4\) : I. See-saw shaped

Sulfur (S) has 6 valence electrons. Fluorine (F) has 7 valence electrons, and there are 4 fluorine atoms. Sulfur forms four single bonds with fluorine atoms, using 4 of its 6 valence electrons. The remaining 2 valence electrons on sulfur form a lone pair. There are 5 electron pairs (4 bonding pairs + 1 lone pair) around the sulfur atom. In a trigonal bipyramidal arrangement, the lone pair occupies an equatorial position because it experiences less repulsion from other pairs in this position. The molecular shape becomes a see-saw due to the presence of the lone pair, which distorts the ideal trigonal bipyramidal geometry.

C. \(BrF_3\) : IV. Bent T shape: 

Bromine (Br) has 7 valence electrons. Fluorine (F) has 7 valence electrons, and there are 3 fluorine atoms. Bromine forms three single bonds with fluorine atoms, using 3 of its 7 valence electrons. The remaining 4 valence electrons on bromine form 2 lone pairs. There are 5 electron pairs (3 bonding pairs + 2 lone pairs) around the bromine atom. In a trigonal bipyramidal arrangement, the lone pairs prefer to occupy equatorial positions because they experience less repulsion there. With the lone pairs in the equatorial positions and the fluorine atoms occupying the axial and remaining equatorial positions, the molecular shape becomes bent T-shaped.

D. \(XeF_4\) : II. Square Planar :

Xenon (Xe) has 8 valence electrons. Fluorine (F) has 7 valence electrons, and there are 4 fluorine atoms. Xenon forms four single bonds with fluorine atoms, using 4 of its 8 valence electrons. The remaining 4 electrons on xenon form 2 lone pairs. There are 6 electron pairs (4 bonding pairs + 2 lone pairs) around the xenon atom. The ideal arrangement for 6 electron pairs is octahedral, but the presence of two lone pairs distorts this arrangement. The two lone pairs occupy positions opposite each other in the octahedral structure, leading to a square planar molecular geometry.

Thus, the correct matching is option 4: A-III, B-I, C-II, D-II.