question_answer 100)

    On moving from left to right in a period in the periodic table, the size of the atom (a) increases                                                                      (b) decreases (c) does not change appreciably                                (d) first decreases and then increases

Answer:

                  (b) Due to large positive charge on the nucleus, the electrons are pulled in more close to the nucleus and the size of the atom decreases. However, the size of atom of an inert gas is bigger than that of the preceding halogen atom. The greater size of the inert gas atom in a period is due to the structural stability of its outermost shell consisting of an octet of electrons.