In the Lothar Meyer curve,the descending position (next to the peak) is held by which of the following?

Explain the Law of Octaves given by Newland.

What will be the formula of '$M$' nitrate based on the given Lothar Meyer curve?

Which elements did Mendeleev leave gaps for in his periodic table and what names did he give them?

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.

Write a note on the genesis of the periodic table.