-Elements in group 2 (alkaline earth metals) have a 2 valence electrons (two electrons in the outermost energy shell). Which means that for these elements to achieve an octet configuration, they will have to loose two electrons. Therefore; element X has a valency electrons, it reacts chlorine to form a compound (XCl2), since chlorine has a valency of 1.
Answer: The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, epochs, and ages.
