How many coordinate bonds are present in SO₃?

To determine the number of coordinate bonds in sulfur trioxide (\(\text{SO}_3\)), let's examine its structure and bonding.

1. **Molecular Structure**:
- Sulfur trioxide (\(\text{SO}_3\)) has a central sulfur atom bonded to three oxygen atoms.
- The molecule is planar and has a trigonal planar geometry.

2. **Bonding in \(\text{SO}_3\)**:
- Sulfur forms three double bonds with three oxygen atoms. In \(\text{SO}_3\), each of these double bonds consists of one sigma (\(\sigma\)) bond and one pi (\(\pi\)) bond.
- Sulfur has an expanded octet, meaning it can accommodate more than eight electrons around it.

3. **Coordinate Bonds**:
- In \(\text{SO}_3\), sulfur uses its vacant d-orbitals to form double bonds with the oxygen atoms. Each oxygen atom has a lone pair of electrons that can be used to form a coordinate bond with sulfur.
- The structure of \(\text{SO}_3\) involves coordinate (or dative) bonds where one of the electrons in the bond pair comes from the oxygen atom, and the other comes from the sulfur atom.

4. **Counting Coordinate Bonds**:
- In each double bond between sulfur and oxygen, the first bond (sigma bond) is formed by the overlap of orbitals, and the second bond (pi bond) involves the sharing of electrons between sulfur and oxygen atoms.
- The formation of each double bond involves one coordinate bond from the oxygen’s lone pair to the sulfur.

Therefore, \(\text{SO}_3\) has three coordinate bonds, one for each double bond with an oxygen atom.