The element of one short period of the periodic table is given below in the order from the left to right.
$\mathrm{L}\mathrm{i}, \mathrm{B}\mathrm{e}, \mathrm{B}, \mathrm{C}, \mathrm{O}, \mathrm{F}, \mathrm{N}\mathrm{e}$
(i) To which period do these elements belong?

(ii) One element of this period is missing. Which is the missing element, and where should it be placed?

(iii) Which one of the elements in this period shows the property of catenation?

(iv) Place fluorine, beryllium, and nitrogen in the increasing order of electronegativity.

(v) Which one of the above elements belongs to the halogen series?