List of top Science Questions on Periodic Table

Explain addition reaction with example.
On going down a group, the size of an atom increases because:
Write the electronic configuration of chlorine (atomic number 17). Explain its position in the periodic table and write its valency.
On moving from left to right in the third period of the periodic table:
How many groups and periods are present in the Modern Periodic Table? In which groups are alkaline metals and inert elements placed in this periodic table?
Moving towards right in Modern Periodic Table:
Alkali metal among the following is:
Match the compounds given in Column A with their examples in Column B.
Alkali metals are: