Classify the following substances into ionic, covalent, molecular or metallic.
MgO, `SO_(2), I_(2) , H_(2)O("ice"), SiO_(2)` (quartz), brass.

Explanation

To classify the given substances into ionic, covalent, molecular, or metallic categories, we can analyze each substance based on its bonding characteristics and structure.

### Step-by-Step Solution:

1. **MgO (Magnesium Oxide)**:
- **Classification**: Ionic
- **Explanation**: Magnesium (Mg) donates two electrons to become Mg²⁺, while oxygen (O) accepts two electrons to become O²⁻. The electrostatic attraction between these oppositely charged ions forms an ionic bond.

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