Statement 1: An atom of valency 2 can combine with 2 other atoms of valency 1. Statement 2: To write the chemical formula, one must know the valency of the element.
Two elements X and Y belong to group 1 and 2 respectively in the same period of periodic table.
Compare them with respect to:
(i)The number of valence electrons in their atoms
(ii)Their valencies
(iii)Metallic character
(iv)The sizes of their atoms
(v)The formulae of their oxides
(vi) The formulae of their chlorides