Correct Answer: Hydrogen

Solution : The correct option is Hydrogen.

Hydrogen is not placed in Group 1 of the Modern Periodic Table. In the Modern Periodic Table, Group 1 elements are known as alkali metals, which include elements like lithium (Li), sodium (Na), potassium (K), and so on. These elements share similar properties, particularly in their reactivity, due to having one valence electron in their outer shell.

Hydrogen, on the other hand, is a unique element. It is often placed at the top of Group 1 for convenience, but it has distinct properties that do not entirely align with those of the alkali metals.