What made mendeleev's periodic table particularly special?

Mendeleev's periodic table particularly special as he orchestrated the components by expanding nuclear mass and put components with comparative properties underneath one another.  

Explanation:

He gathers the components as per their properties adjusted some wrongly assigned nuclear masses. The course of action of components as indicated by their properties left some clear spaces in the table. He expected that the clear spaces spoke to components that had not yet been found.

He utilized his table to foresee the chemical and physical properties of five of the missing components. Three of these components were found in the following 15 years, and their properties firmly coordinated Mendeleev's forecasts. All chemists accepted at these points and acknowledged Mendeleev's Periodic Table.

i think the answer is a and b

i wish you luck

its lower due to the doppler effect.: apex