Out of the elements H(1), Be(4), Na (11), Mg(12) :
(a) Write the pair of elements having similar chemical properties.
(b) State the group number of each pair.
(c) Name one another element belonging to each of these groups.

Explanation

The electronic configuration of the elements are as follows :
H (Z = 1) 1, Be (Z = 4) 2, 2, Na(Z = 11) 2, 8, 1, Mg (Z = 12) 2, 8, 2.
(a) Elements Be and Mg have similar chemical properties since they have two valence electrons. However, elements H and Na donot exhibit similar chemical properties since the position of hydrogen in the periodic table is exceptional. However, these are present in the same group.
(b) Group No. of H and Na : Group 1
Group No. of Be and Mg : Group 2
(c) Another element present in Group 1 is K (Z=19). Similarly another element belonging to group 2 is Ca (Z=20).