Two elements X and Y have atomic numbers 10 and 14 respectively. Identify the group numbers of these elements in the periodic table.
Electronic configurations of X and Y are
X10 = 2, 8
Y14 = 2, 8, 4
Since element X has 8 electrons in outermost shell so it belongs to 18 group and element Y has 4 electrons in outermost shell so it belongs to 14 group.