Which of the following is a Dobereiner triad?

Which scientist used atomic volume as the basis for the periodic classification of elements?

Which of the following is a Dobereiner's triad?

State whether the following statements are true or false:
$(i)$ The chart of elements presented by $Courtois$ could predict the stoichiometry of oxides of some metals.
$(ii)$ $Li, Na, Rb$ are known as $Döbereiner's$ triads.
$(iii)$ In $1863$,$Newlands$ classified the $56$ discovered elements into $18$ groups.
$(iv)$ $Mendeleev's$ periodic table is based on the atomic number of elements.

Name the scientists who contributed to the development of the periodic table and state their respective laws or contributions.

The modern periodic table is based on the atomic number of the elements. The experiment which proved the significance of the atomic number was: