Which scientist used atomic volume as the basis for the periodic classification of elements?

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 .......... .

Which medals were awarded to Newlands and Seaborg for their work?

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

The most important active step in the development of the periodic table was taken by

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