Question

1. choose the best answer. which of these element groups is the least reactive? alkaline earth alkali transition

Explanation:

1. For the first question: Elements in the same vertical column (group) of the periodic table have the same number of valence electrons, which leads to similar chemical properties.
2. For the second question: Transition elements have partially filled d-orbitals, which makes them less reactive compared to alkali (1 valence electron, highly reactive) and alkaline earth (2 valence electrons, very reactive) groups, as their valence electrons are not as easily lost or gained.

Answer:

1. group
2. transition