Merits are as follows:-\xa0i. There was a regular gradation in physical and chemical properties of elements.ii. The group number of an element indicates highest oxidation state that it can attain.iii. There were many vacant spaces in Mendeleev\’s periodic table for the elements to be discovered. He named them Eka-Boron, Eka-Aluminium and Eka-silicone He also predicted the properties of these undiscovered elements including atomic masses. These elements were discovered as Sc ,Ga and Ge with same features as he predicted.iv. Mendeleev’s arrangement helped to correct atomic masses of a number of elements.Demerits of Mendeleev’s periodic tablei. Mendeleev could not assign a correct position to hydrogen in the periodic table as hydrogen resembles alkali metals as well as halogens.ii. Isotopes had to be given the same position in the periodic table though isotopes of the same elements have different atomic masses.iii. It was observed that at certain places, an element of higher atomic mass Cobalt (Co=58.93) has been placed before an element of lower atomic mass Nickel (Ni = 58.71).iv. Some elements placed in the same sub – group varies in their properties. Manganese is placed with halogens which totally differ in the properties.\xa0

Merits are as follows:-\xa01. There was a regular gradation in physical and chemical properties of elements.\xa02. The group number of an element indicates highest oxidation state that it can attain.\xa03. There were many vacant spaces in Mendeleev\’s periodic table for the elements to be discovered. He named them Eka-Boron, Eka-Aluminium and Eka-silicone He also predicted the properties of these undiscovered elements including atomic masses. These elements were discovered as Sc ,Ga and Ge with\xa0same features as he predicted.\xa04. Mendeleev’s arrangement helped to correct atomic masses of a number of elements.Demerits are as follows:-\xa01. The elements, if arranged according to their atomic weights show an evident periodicity of properties.\xa0\xa02. Elements which are similar as regards their chemical properties have atomic weights which are either nearly the same value or which increase regularly.\xa0\xa03. The arrangement of the elements or of groups of elements in the order of their atomic weights, corresponds with their so called valencies.\xa0
Ans is i don\’t know