Name the periods whose elements show diagonal relationship.

Explanation

To answer the question about which periods in the periodic table show diagonal relationships, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Diagonal Relationships**:
Diagonal relationships in the periodic table refer to the similarities in properties between elements that are not in the same group but are located diagonally to each other.

2. **Identifying the Relevant Periods**:
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