Write merits of Mendeleev’s periodic table.
1) Atomic masses of some elements were revised so as to give them proper place in periodic table in accordance with their properties e.g. previous determined atomic mass of berryllium 14.09 has changed to 9.4.
2) Vacant space were coefficient in periodic table that were not discovered at that time and were named as eka-silicon, eka-aluminium, eka-boron... later on after their discovery they were named as germanium, gallium and scandium.
3) Mendeleev also created a zero group without disturbing the original periodic table in which noble gases can be fitted well.