Name the Russian chemist who said that the properties of elements are a periodic functions of their atomic masses.

On what basis are they arranged now?

State whether the following statements are true or false:

(a) Newlands divided the elements into horizontal rows of eight elements each.

(b) According to Mendeleev’s periodic law, the properties of elements are a periodic function of their atomic numbers.

(c) The elements in a group have consecutive atomic numbers.

Rewrite the following statements after correction, if necessary:

(a) Group have elements with consecutive atomic numbers.

(b) Periodic are the horizontal rows of elements.

(c) Isotopes are the elements of the same group.

Name the scientists who gave the following laws in the early classification of elements:

(a) Law of octaves

(b) Law of triads