How is hardness of pencil related to the composition of pencil lead?

Explanation

### Step-by-Step Solution:

1. **Understanding Pencil Composition**:
- Pencils are primarily made up of graphite, clay, and a binder. The typical composition includes about 65% graphite, 30% clay, and 5% binder.

2. **Role of Graphite**:
- Graphite is a soft material. When more graphite is included in the pencil lead, the pencil becomes softer. This is because graphite has a slippery texture that allows it to glide easily on paper.

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