Ans : Kr
Seeing periodic table, elements in the left side is more metallic than the right side(because they have less valence electron, it easily oxidize.)
The lower the element is placed, the more metallic it is because of the size of element is bigger, which leads to lower binding force of valence electron.
The place of the given elements.
Se Br Kr
Sb I
Kr is the least metallic element among them.
