State one reason for keeping fluorine and chlorine in the same group group of the periodic table.

Justify the mentioning two reasons, the inclusion of Ca and Mg in the same group of the periodic table.

No. of groups in long periodic table-

Assertion (A) : Separation of Zr and Hf is difficult. Reason (R ) : Zr and Hf lies in the same group of the periodic table.

Mention one similarity in atoms of the elements belonging to the same group of the periodic table.

What is the importance of zero group in periodic table?

Which one is a tracheate group

Which one of the following does not increase while moving down the group of the periodic table?

Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation.