Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:
a wall

Explanation

To classify a wall as opaque or transparent, and luminous or non-luminous, we can follow these steps:

### Step 1: Determine if the wall is opaque, transparent, or translucent.
- **Definition of Opaque**: Opaque objects do not allow light to pass through them.
- **Definition of Transparent**: Transparent objects allow light to pass through without scattering.
- **Definition of Translucent**: Translucent objects allow some light to pass through but scatter it, preventing a clear image.

**Conclusion for Step 1**: A wall is classified as **opaque** because it does not allow light to pass through.
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