With reference of first three periods of the periodic table.
Metalloid in 3rd period

Explanation

To determine the metalloid in the third period of the periodic table, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Metalloids**:
- Metalloids are elements that exhibit properties of both metals and non-metals. They are typically found between metals and non-metals in the periodic table.

2. **Identify the Structure of the Periodic Table**:
...