Answer:
First and seventeenth group.
Explanation:
Hydrogen is a special case as it has only one electron in its outermost orbital.
The hydrogen can lose or can accept electron easily.
Thus it can form positive ion similar to alkali metals and negative ion similar to halogens.
Thus it can fall into two groups
a) I group [Alkali metals]
b) 17th Group [Halogens]
