1. We should draw a Lewis structure of PCl3F2
Number of valence electrons: 5(P) + 7(Cl)*3 + 7(F)*2 = 40.
Draw a Lewis structure. For each element add nesessary number of electrons to make full octet, for P as the element od third period the octet is expanded.
2. We should use VSEPR theory to explain molecular structure.
We should count number of bounding pairs of electrons and number of lone pairs of electrons around the central atom (P atom)
Number of bounding pairs is 5
Number of lone pairs O
Molecular geometry AX5
According to VSEPR theory molecular structure is trigonal bipyramid with bond angles 900 and 120