Which of the following matter falls in the category of mixtures? Ice, milk, brass, iron, air, petrol, mercury, calcium oxide.

Explanation

To determine which of the following substances fall under the category of mixtures, we will analyze each option provided: ice, milk, brass, iron, air, petrol, mercury, and calcium oxide.

### Step-by-Step Solution:

1. **Understanding Mixtures**:
- Mixtures are combinations of two or more substances where each substance retains its own properties. They can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).

2. **Analyzing Each Substance**:
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