The number of periods present in the Modern Periodic table are _______ .
5
7
18
9
Modern Periodic table contains 7 periods.
What is the number of elements in the :
(a) Ist period, and
(b) 3rd period, of the modern periodic table ?
(a) State the modern periodic law.
(b) How many periods and groups are there in the modern periodic table?
In modern periodic table, the atom of the element present at the end of each period has a/an _____ valence shell.