The electrons present in the outermost orbit of an atom are called ___________.

The correct answer is C. Valence electrons.

The electrons present in the outermost orbit of an atom are called valence electrons. For example, aluminium has 3 electrons in the outermost orbit so its valence electrons are 3. These electrons are crucial because they are involved in chemical bonding and reactions. The number of valence electrons determines an element’s reactivity, how it bonds with other elements, and its overall chemical properties.

For example, in the case of hydrogen (H), the atom has one electron in its outermost shell, which makes it highly reactive. Similarly, elements in the same group of the periodic table have the same number of valence electrons, which is why they exhibit similar chemical behavior.

In summary, valence electrons are the outermost electrons responsible for an atom's chemical characteristics, and they play a key role in forming bonds with other atoms.