The elements `_(4)Be,_(12)Mgand_(20)Ca` each having two, valence electrons in their valence shells are in periods 2, 3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case,
(i) In which group should they be?
(ii) Which one of them is least reactive ?
(iii) Which one of them has the largest atomic size ?

Explanation

(i) They all belong to group 2 because all three have 2 electrons in their outermost shell.
(ii) Be is least reactive because it has 2 shells and due to more nuclear change it is not easy to take electrons from it.
(iii) Ca is the element having largest atomic radius because it has 4 shells.