Question

why hydrogen is added in 1-A group of periodic table even though it shows the similar properties of 7-A group

Answer 1

Hydrogen is a non metal and is placed above group in periodic table because it has ns1 electronic configuration like alkali metals.

Answer 2

Even though hydrogen shows similar properties of 7-A group elements it is placed in 1-A group because it has atomic number 1
It's properties resemble the ones of alkali metals.
It doesn't have all alkali metal properties also
For ex: its is gas at room temperature but alkali metals are solids.