To determine which of the following molecules has a trigonal pyramidal shape, we need to understand the molecular geometry of each option. The molecular shape can be predicted using the Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that electron pairs around a central atom will position themselves as far apart as possible to minimize repulsion.
Let's consider each option:
### Option A: Cl-S (Chlorine-sulfur)
1. Sulfur (S) is the central atom.
2. Chlorine (Cl) is bonded to sulfur.
3. Sulfur has 6 valence electrons, and after forming one bond with chlorine, it has three lone pairs left.
4. The molecular geometry considering three bonded pairs and one lone pair is trigonal pyramidal.
### Option B: CO (Carbon monoxide)
1. Carbon (C) is the central atom.
2. Oxygen (O) is bonded to carbon.
3. Carbon has 4 valence electrons, forming a triple bond with oxygen, leaving one lone pair on oxygen.
4. This results in a linear shape, not trigonal pyramidal.
### Option C: CO₂ (Carbon dioxide)
1. Carbon (C) is the central atom.
2. Two Oxygen (O) atoms are bonded to carbon.
3. Carbon forms double bonds with each oxygen, with no lone pairs remaining on the central atom.
4. The shape is linear, as it has a symmetric arrangement, not trigonal pyramidal.
### Option D: Ni(CO)₄ (Nickel tetracarbonyl)
1. Nickel (Ni) is the central atom.
2. Four carbon monoxide (CO) molecules are bonded to nickel.
3. Nickel with 10 valence electrons typically forms complexes in a tetrahedral arrangement.
4. The shape is tetrahedral, not trigonal pyramidal.
After evaluating all the options, we can conclude that the molecule that has a trigonal pyramidal shape is:
### Answer: A. Cl-S
