In the Modern Periodic Table, the position of which element is anomalous as it can be placed in either group 1 or group 17?

1. Hydrogen has one electron, like group 1 alkali metals. 2. It also needs one electron to complete its shell, like group 17 halogens. 3. So hydrogen's position is anomalous. _Source: RRB Group D CEN-02/2018 PYQ, Q.15._