The number of species having non-pyramidal shape among the following is:
(A) SO$$_3$$
(B) NO$$_3^-$$
(C) PCl$$_3$$
(D) CO$$_3^{2-}$$

The correct answer is 3.

According to NCERT Class 11 Chemistry, Chapter 4: Chemical Bonding and Molecular Structure:

"The shape of a molecule depends upon the number of valence shell electron pairs (bonded or nonbonded) around the central atom."

To determine the shape and hybridization, we evaluate the number of bond pairs and lone pairs around the central atom for each species:

• (A) SO₃: The central sulfur atom has 3 bond pairs and 0 lone pairs. The hybridization is sp² and the shape is trigonal planar, which is non-pyramidal.
• (B) NO₃⁻: The central nitrogen atom has 3 bond pairs and 0 lone pairs. The hybridization is sp² and the shape is trigonal planar, which is non-pyramidal.
• (C) PCl₃: The central phosphorus atom has 3 bond pairs and 1 lone pair. The hybridization is sp³ and the shape is trigonal pyramidal.
• (D) CO₃²⁻: The central carbon atom has 3 bond pairs and 0 lone pairs. The hybridization is sp² and the shape is trigonal planar, which is non-pyramidal.

Hence, the species SO₃, NO₃⁻, and CO₃²⁻ are non-pyramidal.

Therefore, the total number of species having a non-pyramidal shape is 3.