The law of triads was introduced by

Addition of oxygen is called

The basis of modern periodic table is

The  first period has only _________ elements.

The outermost electronic configuration of alkali metals is

The eighth  element is a kind  of repetition of the first,  like the eighth note of an  octave in music.  This law is proposed by 

Which element has largest atomic radius?

Lanthanoids are

d- block elements are also called

Which element has the smallest size.