What were the criteria used by Mendeleev in creating his periodic table?

The criteria used by Mendeleev in creating his Periodic Table are: (i) Elements were arranged in the increasing order of their atomic masses. (ii) All elements in a group should have similar chemical properties. That is, he used the criteria that the element with similar chemical properties should be in the same group.

Who proposed the law of Octaves?

The law of Octaves was proposed by the British chemist John Newlands. According to the law of octaves, when elements are arranged in increasing order of their atomic masses, the properties of the eighth element are a repetition of the properties of the first element.

What is the basis of the classification of elements of the modern periodic table?

The basis of the classification of elements of the modern periodic table is the atomic number of the elements. The modern periodic law states that the physical and chemical properties of elements are the periodic function of their atomic numbers. The atomic number is the number of protons in an atom and this number is unique for each element. So, in the modern periodic table, elements are arranged in horizontal rows with their increasing atomic numbers.