PO(OH)₃ - Phosphoric acid - also H₃PO₄ :

First draw the Lewis dot structure:


Electron geometry: tetrahedral. Hybridization: sp³

Then draw the 3D molecular structure using VSEPR rules:


Decision:
The molecular geometry of PO(OH)₃ is tetrahedral with asymmetric charge distribution on the central atom.
Therefore this molecule is polar.

Phosphoric acid on Wikipedia.

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