Given below are some elements of the modern periodic table. Atomic number of the element is given in the parentheses : A(4), B(9), C(14), D(19), E(20) (a) Select the element that has one electron in the outermost shell, Also write the electronic configuration of this element. (b) Which two elements amongst these belong to the same group ? Give reason for your answer. (c) Which two elements amongst these belong to the same period ? Which one of the two has bigger atomic radius?