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Answer -
(a) Element with 5 electrons in outer subshell is havingelectronic configuration ns2np5. Halogen group is having the sameelectronic configuration. So, the elements can be At, I, Br, Cl and F.
(b) The elements that tend to gain 2 electrons are those who canachieve stable inert gas configuration by gaining these electrons. They arehaving electronic configuration ns2np4. Oxygen containing group is having thesame electronic configuration.
(c) The elements that tend to expel 2 electrons are those whocan achieve stable inert gas configuration by expelling these electrons. Theyare having electronic configuration ns2.2nd Group elements are havingthe same electronic configuration. So, the elements can be Ba, Sr, Ca, Mg, Be.
(d) Elements of group 17 are having liquid, gas, metal andnon-metals as well at room temperature.