Answer:
(i) some element be grouped in sets of three elemets in the increasing order of their atomic weeghts in which the atomic weight of the middle element was found to be the arithmetic mean of the atomic weight of the other two elements
(ii) when the elements are arranged in the increasing order of their atomic weight the eight element resembles the first in physical and chmeical porerties just as the eighth note on a musical scale resembles the first one
(iii) The physical and chemical properites of elements are periodic functions of thei atomic weights
(iv) The physical and chemical properites of elecments are periodic function of their atomic number
