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.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.