"The properties of the elements are periodic function of their atomic numbers." This statement was given by:

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.

Describe Mendeleev's periodic table.

Fill in the blanks given below:
$(i)$ The first scientist to think about the properties of elements was ......... .
$(ii)$ The relationship of properties of elements suggested by Dobereiner is known as ........... .
$(iii)$ The Law of Octaves was proposed by the chemist ......... .
$(iv)$ The first periodic table was constructed by .......... and .......... .

Explain the "Law of Triads" with examples.

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