Out of `SO_(2),BeCl_(2),O_(3),H_(2)O and HgCl_(2),` the linear species are:

Options

A. `SO_(2) and O_(3)`
B. `SO_(2) and H_(2)O`
C. `BeCl_(2) and HgCl_(2)`
D. `O_(3) and H_(2)O`

Explanation

To determine which of the given molecules are linear, we will analyze the molecular geometry of each compound: SO₂, BeCl₂, O₃, H₂O, and HgCl₂.

### Step-by-Step Solution:

1. **Analyze SO₂ (Sulfur Dioxide)**:
- Sulfur (S) has 6 valence electrons and forms two double bonds with two oxygen (O) atoms.
- There is one lone pair of electrons on the sulfur atom.
- The molecular geometry is bent due to the presence of the lone pair.
- **Conclusion**: SO₂ is not linear.

2. **Analyze BeCl₂ (Beryllium Chloride)**:
- Beryllium (Be) has 2 valence electrons and forms two single bonds with two chlorine (Cl) atoms.
- There are no lone pairs on the beryllium atom.
- The molecular geometry is linear because there are only two bonding pairs and no lone pairs.
- **Conclusion**: BeCl₂ is linear.

3. **Analyze O₃ (Ozone)**:
- Ozone consists of three oxygen atoms. The central oxygen atom forms a bond with two outer oxygen atoms.
- There is one lone pair on the central oxygen atom.
- The molecular geometry is bent due to the lone pair.
- **Conclusion**: O₃ is not linear.

4. **Analyze H₂O (Water)**:
- Water has two hydrogen (H) atoms bonded to an oxygen atom.
- There are two lone pairs on the oxygen atom.
- The molecular geometry is bent due to the presence of the lone pairs.
- **Conclusion**: H₂O is not linear.

5. **Analyze HgCl₂ (Mercury(II) Chloride)**:
- Mercury (Hg) has 2 valence electrons and forms two single bonds with two chlorine (Cl) atoms.
- There are no lone pairs on the mercury atom.
- The molecular geometry is linear because there are only two bonding pairs and no lone pairs.
- **Conclusion**: HgCl₂ is linear.

### Final Answer:
The linear species among the given options are **BeCl₂ and HgCl₂**.