What was the basis for Mendeleev's classification of elements in his periodic table?

State whether the following statements are true or false:
$(i)$ The first periodic table was proposed by Dobereiner.
$(ii)$ The law of octaves was proposed by Newlands in $1865$.
$(iii)$ Mendeleev was the first to propose the periodic law.
$(iv)$ Mendeleev named Eka-aluminium as Germanium and Eka-silicon as Gallium.

Which of the following information was not known at the time when Mendeleev's periodic table was constructed?

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

Explain the contribution of Newlands to the periodic table.