Molecular shape of SOCl2 is Trigonal pyramidal.

Explanation:
SOCl2 is the chemical formula for thionyl chloride. It consists of one sulfur atom (S), one oxygen atom (O), and two chlorine atoms (Cl). To determine the molecular shape of SOCl2, we need to consider the arrangement of the atoms around the central sulfur atom.

- Central atom: Sulfur (S)
- Surrounding atoms: Oxygen (O) and two Chlorine (Cl) atoms

1. Lewis structure:
First, let's draw the Lewis structure of SOCl2 to determine the arrangement of the valence electrons. The Lewis structure shows the bonding and non-bonding electron pairs around the central atom.

- Sulfur (S) has 6 valence electrons.
- Oxygen (O) has 6 valence electrons.
- Chlorine (Cl) has 7 valence electrons each.

When we combine these atoms, we get:

O Cl Cl
\ | /
S

To complete the octet of sulfur, one of the oxygen atoms forms a double bond with sulfur, and the other two atoms (one oxygen and one chlorine) form single bonds. This leaves one lone pair of electrons on the sulfur atom.

2. Electron pair geometry:
To determine the electron pair geometry, we need to consider both the bonded and lone pair electrons around the central atom.

In SOCl2, we have:
- 1 double bond (2 electron pairs) between S and O
- 2 single bonds (2 electron pairs) between S and Cl
- 1 lone pair (2 electron pairs) on S

So, the total number of electron pairs around the central atom is 6.

3. Molecular shape:
The molecular shape is determined by the arrangement of these electron pairs. In this case, the electron pair geometry is trigonal bipyramidal.

However, we need to consider the positions of the bonded and lone pairs in this geometry to determine the actual molecular shape.

In SOCl2, we have:
- 1 bonded pair (double bond) and 3 bonded pairs (single bonds)
- 1 lone pair

The presence of a lone pair causes repulsion, which results in the distortion of the electron pair geometry. The lone pair occupies more space than the bonded pairs, pushing the bonded pairs closer together.

As a result, the molecular shape of SOCl2 is trigonal pyramidal, where the three chlorine atoms and the lone pair are positioned in a pyramid-like arrangement around the central sulfur atom.

Therefore, the correct answer is option B: Trigonal pyramidal.