This question involves analyzing molecular geometry, boiling points, and bond angles in phosphorus oxyhalides and related compounds. Let's break down each statement step by step.

Statement 1: POF₂Cl is pyramidal

POF₂Cl has a central phosphorus atom bonded to one oxygen (double bond), two fluorine atoms, and one chlorine atom. The hybridization of phosphorus is sp³ due to four electron domains (one double bond counts as one domain). The molecular geometry is tetrahedral, but since one position is occupied by a double-bonded oxygen, the shape around phosphorus is trigonal pyramidal (similar to ammonia, NH₃). This statement is correct.

Statement 2: Boiling point of PO(NCO)₃ is more than PO(NCS)₃

Boiling point depends on molecular mass and intermolecular forces. PO(NCO)₃ (molecular mass ≈ 229 g/mol) has NCO groups, while PO(NCS)₃ (molecular mass ≈ 257 g/mol) has heavier NCS groups. Higher mass usually increases boiling point, but NCS groups might have stronger London dispersion forces due to larger size. However, NCO is smaller and less polarizable, so PO(NCS)₃ should have a higher boiling point. This statement is incorrect.

Statement 3: Boiling point of POCl₃ is less than POBr₃

POCl₃ (molecular mass ≈ 153.5 g/mol) and POBr₃ (molecular mass ≈ 286.5 g/mol) are similar in structure. POBr₃ has higher molecular mass and larger bromine atoms, leading to stronger London dispersion forces and thus a higher boiling point. POCl₃ boiling point is indeed lower. This statement is correct.

Statement 4: Bond angle in POF₃ is less than POCl₃

Both POF₃ and POCl₃ have tetrahedral electron geometry with sp³ hybridization. The bond angle (e.g., F-P-F vs Cl-P-Cl) is influenced by the size and electronegativity of substituents. Fluorine is more electronegative than chlorine, so in POF₃, the bonding electrons are pulled closer to fluorine, reducing electron density at phosphorus and decreasing bond angles due to increased lone pair-bond pair repulsion. In POCl₃, chlorine is less electronegative, so bond angles are larger. Thus, bond angle in POF₃ is less than in POCl₃. This statement is correct.

Related Topics

Molecular Geometry: Determined by VSEPR theory based on electron domains around the central atom.

Intermolecular Forces: London dispersion, dipole-dipole, and hydrogen bonding affect boiling points.

Electronegativity and Bond Angles: Higher electronegativity of substituents can reduce bond angles due to increased repulsion.

Formulae

VSEPR theory: Electron domains = bonding pairs + lone pairs. Geometry depends on the number of domains.

Boiling point correlation: Higher molecular mass and larger atomic size increase boiling point.

Bond angle trend: More electronegative substituents decrease bond angles in similar molecules.