Among the following how many of the molecules are linear.
`CO_(2), NO_(2)^(-), SO_(2), N_(3)^(-), C_(2)H_(2), I_(3)^(-), XeF_(2), CS_(2)`

Answer

To determine how many of the given molecules are linear, we will analyze each molecule one by one, considering their molecular geometry and the presence of lone pairs.

### Step-by-Step Solution:

1. **CO₂ (Carbon Dioxide)**:
- Structure: O=C=O
- Geometry: Linear (no lone pairs on the central atom).
- Conclusion: Linear.

2. **NO₂⁻ (Nitrite Ion)**:
- Structure: O=N-O⁻ (with a lone pair on nitrogen).
- Geometry: Bent (due to the lone pair on nitrogen).
- Conclusion: Not linear.

3. **SO₂ (Sulfur Dioxide)**:
- Structure: O=S=O (with a lone pair on sulfur).
- Geometry: Bent (due to the lone pair on sulfur).
- Conclusion: Not linear.

4. **N₃⁻ (Azide Ion)**:
- Structure: N≡N-N⁻
- Geometry: Linear (no lone pairs on the central nitrogen).
- Conclusion: Linear.

5. **C₂H₂ (Acetylene)**:
- Structure: H-C≡C-H
- Geometry: Linear (triple bond between carbon atoms).
- Conclusion: Linear.

6. **I₃⁻ (Triiodide Ion)**:
- Structure: I-I-I (with three lone pairs on the central iodine).
- Geometry: Linear (the three lone pairs are arranged to minimize repulsion).
- Conclusion: Linear.

7. **XeF₂ (Xenon Difluoride)**:
- Structure: F-Xe-F (with three lone pairs on xenon).
- Geometry: Linear (the three lone pairs are arranged in a trigonal bipyramidal geometry, with the fluorine atoms opposite each other).
- Conclusion: Linear.

8. **CS₂ (Carbon Disulfide)**:
- Structure: S=C=S
- Geometry: Linear (no lone pairs on the central carbon).
- Conclusion: Linear.

### Summary of Linear Molecules:
- Linear Molecules: CO₂, N₃⁻, C₂H₂, I₃⁻, XeF₂, CS₂
- Total Linear Molecules: 6

### Final Answer:
**There are 6 linear molecules among the given options.**

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