Some versions of the periodic table show hydrogen at the top of Group 1A (1) and at the top of Group 7A (17). What properties of hydrogen justify each of these placements?

Answer:Hydrogen is placed such because it exhibits some similar characteristics of both group1 and group VII elements.

Explanation:

The reason why hydrogen is similar to group 1 metals:

#It has same valence electron and inorder achieve octet state it can lose that electron and forms H + ion

#It acts as a good reducing agent similar to group1 metals

#It can also halides

Similarity to halogens:

#hydrogen can also gain one electron to gain noble gas configuration. It can combine with other non metals to form molecules with covalent bonding.

#It exists as diatomin molecule, H2

#Have the same electronegativity nature

#its reaction with other metal