An element X belongs to the 3rd period and group 2. The nature of an element is:

An element X belongs to the 3rd period and group 2. The nature of an element is metal.

• Elements in group 2 of the periodic table are known as the alkaline earth metals.
•  These elements have two valence electrons in their outermost energy level, which makes them chemically reactive but not as reactive as the alkali metals in group 1. 
• Alkaline earth metals typically have properties like high melting and boiling points, low electronegativity, and they readily form 2⁺ cations by losing their two valence electrons.
• Since X is in group 2, it exhibits the characteristic properties of an alkaline earth metal, which includes being a metallic element.

The group 2 elements are known as alkaline earth metals because they form basic compounds.
An element X belongs to the 3rd period and group 2. The nature of an element is Magnesium.