Boron shows diagonal relationship with ....................

Explanation

**Step-by-Step Solution:**

1. **Understanding Diagonal Relationship**:
- A diagonal relationship in the periodic table refers to the similarity in properties of elements that are situated diagonally to each other. This is often observed between elements in the second and third periods of the periodic table.

2. **Identifying Boron**:
- Boron (B) is located in group 13 (IIIA) and period 2 of the periodic table.

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