The law of triads is applicable to a group of

Explain the contribution of Newlands to the periodic table.

Briefly describe the contributions of various scientists to the development of the Periodic Table.

The modern periodic table,based on the experiment of atomic number which highlights the significance of atomic number,is associated with:

Fill in the blanks given below:
$(i)$ The first scientist to think about the properties of elements was ......... .
$(ii)$ The relationship of properties of elements suggested by Dobereiner is known as ........... .
$(iii)$ The Law of Octaves was proposed by the chemist ......... .
$(iv)$ The first periodic table was constructed by .......... and .......... .

Given below are the atomic masses of the elements:

Element	$Li$	$Na$	$Cl$	$K$	$Ca$	$Br$	$Sr$	$I$	$Ba$
Atomic Mass $(g \cdot mol^{-1})$	$7$	$23$	$35.5$	$39$	$40$	$80$	$88$	$127$	$137$

Which of the following does not form a $Dobereiner's$ triad?