The atomic masses of $Cl$ and $I$ are $35.5$ and $127$ respectively. According to Dobereiner's law of triads,the atomic mass of $Br$ will be ............ .

What is the basic difference in approach between the Mendeleev's Periodic Law and the Modern Periodic Law?

Who stated that the properties of elements are a periodic function of their atomic number?

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.

Which of the following is a Dobereiner triad?

Explain the Law of Octaves given by Newland.