Amongst the following, the number of species having the linear shape is
XeF$$_2$$, I$$_3^+$$, C$$_3$$O$$_2$$, I$$_3^-$$, CO$$_2$$, SO$$_2$$, BeCl$$_2$$ and BCl$$_2^\ominus$$

We need to determine which of the given species have a linear shape.

1. XeF₂: Xe has 8 valence electrons (including 2 bond pairs + 3 lone pairs). Geometry: trigonal bipyramidal electron pair, linear molecular shape. ✓

2. I₃⁺: Total valence electrons = 3(7) − 1 = 20. Central I: 2 bond pairs + 2 lone pairs → bent. ✗

3. C₃O₂ (carbon suboxide): Structure: O=C=C=C=O. All carbons are sp hybridized. Linear. ✓

4. I₃⁻: Total valence electrons = 3(7) + 1 = 22. Central I: 2 bond pairs + 3 lone pairs → sp³d, linear. ✓

5. CO₂: O=C=O. Carbon is sp hybridized. Linear. ✓

6. SO₂: S has 2 bond pairs + 1 lone pair → bent. ✗

7. BeCl₂: Be has 2 bond pairs, no lone pairs → sp, linear. ✓

8. BCl₂⁻: B has 3 + 1 = 4 valence electrons. With 2 bonds: 2 bond pairs + 1 lone pair → sp², bent. ✗

Linear species: XeF₂, C₃O₂, I₃⁻, CO₂, BeCl₂ = 5

The correct answer is 5.