Answer: be found in group 17 and be highly reactive
Explanation:
Elements are distributed in groups and periods in a periodic table.
Elements that belong to same groups will show similar chemical properties because they have same number of valence electrons.
Flourine, chlorine, bromine and iodine are elements which belong to Group 17. All of them contain 7 valence electrons each and need one electron to complete their octet.
The chemical reactivity of elements is governed by the valence electrons present in the element and thus all of them are highly reactive.
Each piece of magnet has only two poles, one north and one south. So if you break a bar magnet into two halves, the piece initially consisting the north pole at the edge automatically creates the south pole at the break point and the part consisting south pole creates North pole at the edge. So each piece has 2 poles.
