Question
Question: Match the Column **Column-I** (A) $\text{ICl}_3$ (B) $\text{AlCl}_3$ (C) $\text{AlF}_3$ (D) $\text...
Match the Column
Column-I
(A) ICl3 (B) AlCl3 (C) AlF3 (D) NO2
Column-II
(p) Hybridisation of central atom is similar in both dimer and monomer form. (q) Both monomer and dimer forms are planar (r) In dimer form all atoms are sp3 hybridised. (s) Does not exist in dimer form

Hybridisation of central atom is similar in both dimer and monomer form.
Both monomer and dimer forms are planar
In dimer form all atoms are sp3 hybridised.
Does not exist in dimer form
A - (p), (q) B - (r) C - (s) D - (p), (q)
Solution
The question asks to match the compounds in Column-I with their properties in Column-II. We will analyze each compound individually.
Analysis of Column-I Compounds:
(A) ICl₃:
- Monomer (ICl₃):
- Central atom: Iodine (I). Valence electrons = 7.
- Number of bond pairs = 3 (with 3 Cl atoms).
- Number of lone pairs = (7 - 3)/2 = 2.
- Steric Number (SN) = 3 (bp) + 2 (lp) = 5.
- Hybridization: sp³d.
- Electron geometry: Trigonal bipyramidal.
- Molecular geometry: T-shaped.
- Planarity: A T-shaped molecule is planar.
- Dimer (I₂Cl₆):
- ICl₃ dimerizes to form I₂Cl₆, which has a structure similar to Al₂Cl₆, but it is planar (D₂h symmetry).
- In I₂Cl₆, each Iodine atom is bonded to 4 Chlorine atoms (2 terminal, 2 bridging).
- For each Iodine, considering 4 bond pairs and 1 lone pair (to satisfy the octet expansion and diamagnetism), the Steric Number = 4 (bp) + 1 (lp) = 5.
- Hybridization: sp³d.
- Planarity: The I₂Cl₆ dimer is planar.
- Matching Properties:
- (p) Hybridisation of central atom is similar in both dimer and monomer form: Yes, I is sp³d in both ICl₃ and I₂Cl₆.
- (q) Both monomer and dimer forms are planar: Yes, ICl₃ (T-shaped) and I₂Cl₆ (D₂h) are both planar.
- (r) In dimer form all atoms are sp³ hybridised: No, Iodine is sp³d.
- (s) Does not exist in dimer form: No, it exists as I₂Cl₆.
- Conclusion for (A): (p), (q)
(B) AlCl₃:
- Monomer (AlCl₃):
- Central atom: Aluminum (Al). Valence electrons = 3.
- Number of bond pairs = 3 (with 3 Cl atoms).
- Number of lone pairs = 0.
- Steric Number (SN) = 3.
- Hybridization: sp².
- Molecular geometry: Trigonal planar.
- Planarity: Planar.
- Dimer (Al₂Cl₆):
- AlCl₃ dimerizes to form Al₂Cl₆, which has a bridged structure.
- In Al₂Cl₆, each Aluminum atom is bonded to 4 Chlorine atoms (2 terminal, 2 bridging).
- For each Al, Steric Number = 4 (bp) + 0 (lp) = 4.
- Hybridization: sp³.
- Planarity: The Al₂Cl₆ dimer is non-planar (tetrahedral geometry around each Al).
- Hybridization of bridging Cl atoms: Each bridging Cl forms 2 bonds and has 2 lone pairs. SN = 2 (bp) + 2 (lp) = 4. Hybridization: sp³.
- Hybridization of terminal Cl atoms: Each terminal Cl forms 1 bond and has 3 lone pairs. SN = 1 (bp) + 3 (lp) = 4. Hybridization: sp³.
- Matching Properties:
- (p) Hybridisation of central atom is similar in both dimer and monomer form: No, Al is sp² in monomer and sp³ in dimer.
- (q) Both monomer and dimer forms are planar: No, the dimer is non-planar.
- (r) In dimer form all atoms are sp³ hybridised: Yes, Al, bridging Cl, and terminal Cl are all sp³ hybridized.
- (s) Does not exist in dimer form: No, it exists as Al₂Cl₆.
- Conclusion for (B): (r)
(C) AlF₃:
- Nature: AlF₃ is a highly ionic compound. In the solid state, it forms a giant polymeric network structure where each Al³⁺ ion is octahedrally coordinated by 6 F⁻ ions. It does not exist as discrete monomeric AlF₃ molecules or dimeric Al₂F₆ molecules in the gas phase under normal conditions.
- Matching Properties:
- (p) Hybridisation of central atom is similar in both dimer and monomer form: Not applicable, as it doesn't form discrete monomer/dimer.
- (q) Both monomer and dimer forms are planar: Not applicable.
- (r) In dimer form all atoms are sp³ hybridised: Not applicable.
- (s) Does not exist in dimer form: Yes, it exists as a polymeric network, not a discrete dimer.
- Conclusion for (C): (s)
(D) NO₂:
- Monomer (NO₂):
- Central atom: Nitrogen (N). Valence electrons = 5.
- It's an odd-electron molecule. It has one double bond and one single bond to oxygen atoms, and one unpaired electron.
- Hybridization: sp² (N forms 2 sigma bonds and has 1 unpaired electron, and a p-orbital for pi bonding).
- Molecular geometry: Bent.
- Planarity: A bent molecule is planar.
- Dimer (N₂O₄):
- NO₂ dimerizes to form N₂O₄.
- In N₂O₄, each Nitrogen atom is bonded to 2 Oxygen atoms and 1 other Nitrogen atom.
- For each N, it forms 3 sigma bonds.
- Steric Number (SN) = 3.
- Hybridization: sp².
- Planarity: N₂O₄ is a planar molecule.
- Matching Properties:
- (p) Hybridisation of central atom is similar in both dimer and monomer form: Yes, N is sp² in both NO₂ and N₂O₄.
- (q) Both monomer and dimer forms are planar: Yes, NO₂ (bent) and N₂O₄ (planar) are both planar.
- (r) In dimer form all atoms are sp³ hybridised: No, Nitrogen is sp².
- (s) Does not exist in dimer form: No, it exists as N₂O₄.
- Conclusion for (D): (p), (q)
Final Match: (A) - (p), (q) (B) - (r) (C) - (s) (D) - (p), (q)
The final answer is A−(p,q);B−(r);C−(s);D−(p,q)
Explanation of the solution:
- ICl₃: Monomer (T-shaped, planar, I is sp³d). Dimer (I₂Cl₆, planar, I is sp³d). Thus, hybridization is similar, and both are planar.
- AlCl₃: Monomer (Trigonal planar, Al is sp²). Dimer (Al₂Cl₆, non-planar, Al is sp³). In the dimer, all atoms (Al, bridging Cl, terminal Cl) are sp³ hybridized.
- AlF₃: Forms a polymeric network in solid state, does not exist as discrete monomer or dimer molecules.
- NO₂: Monomer (Bent, planar, N is sp²). Dimer (N₂O₄, planar, N is sp²). Thus, hybridization is similar, and both are planar.