Answer :
(a) [tex]AlH_3[/tex]
In this Lewis dot structure, there are 3 bond pair and 0 lone pair on the central atom. The total number of electron pair is 3. So, the hybridization of the molecule will be, [tex]sp^2[/tex] and the geometry will be, trigonal planar.
(b) [tex]CH_2F_2[/tex]
In this Lewis dot structure, there are 4 bond pair and 0 lone pair on the central atom. The total number of electron pair is 4. So, the hybridization of the molecule will be, [tex]sp^3[/tex] and the geometry will be, tetrahedral.
(c) [tex]PH_3[/tex]
In this Lewis dot structure, there are 3 bond pair and 1 lone pair on the central atom. The total number of electron pair is 4. So, the hybridization of the molecule will be, [tex]sp^3[/tex] but the the fourth position will be occupied by one lone pair. Hence, the geometry will be, trigonal pyramidal not tetrahedral.
(d) [tex]O_3[/tex]
In this Lewis dot structure, there are 2 bond pair and 1 lone pair on the central atom. The total number of electron pair is 3. So, the hybridization of the molecule will be, [tex]sp^2[/tex] but the the third position will be occupied by one lone pair. Hence, the geometry will be, bent not linear.
The image is also shown below.
