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

What is the fundamental difference between Mendeleev's periodic law and the modern periodic law?

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.

$Li, Na, K$ form a Dobereiner's triad. If the atomic masses of $Li$ and $K$ are $7$ and $39$ respectively,what will be the atomic mass of $Na$?

Write a note on the genesis of the periodic table.

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