Chlorine and element x have similar chemical properties. an atom of element x could have an electron configuration of
(1) 2-2 (2) 2-8-1 (3) 2-8-8 (4) 2-8-18-7

Option (4) is the correct answer.

Explanation:

Chemical properties depend on the number of electrons present in the valence shell.

Atomic number of chlorine is 17 and electrons present in its shells are distributed as 2, 8, 7. So, there are 7 electrons present in the outermost shell.

Therefore, the atom which will also have 7 electrons present in its outermost shell or valence shell will have similar chemical properties as that of chlorine.

Hence, out of the given options atom with electronic configuration 2-8-18-7 will have similar chemical properties.