Solution:
Concept- All elements are represented by a chemical symbol and are arranged in order of increasing atomic number in the periodic table.An element can be easily identified by its atomic number.
Metals are elements placed on the left side of the periodic table and they are capable of forming positive ions by losing their valence electrons.
Non-metals are the elements found on the right of the periodic table (except Hydrogen). They are capable of forming negative ions because of their high electronegativity compared to metals. They usually have 4,5,6, or 7 valence electrons.
Now, the element with atomic number 17 belongs to group 17 and period 3. So, it is Chlorine. And chlorine is non-metal.
Therefore, X is a non-metal.
Hence, the correct answer is 2.
