Final answer:
Beryllium (Be) is less reactive than calcium (Ca), magnesium (Mg), and lithium (Li). The correct answer is a beryllium (Be).
Step-by-step explanation:
The alkaline earth metal that is less reactive than the others from the given options is beryllium (Be).
Alkaline earth metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and while all of them are reactive, beryllium is the least reactive among the given choices.
Compared to calcium (Ca), magnesium (Mg), and lithium (Li), beryllium has a higher ionization energy, making it less likely to lose its valence electrons and therefore less reactive.
To determine which of the following elements is less reactive than the others - beryllium (Be), calcium (Ca), lithium (Li), and magnesium (Mg) - we need to look at their positions in the periodic table and their properties.
Beryllium, magnesium, and calcium are part of the Group 2 alkaline earth metals, which means they are reactive but less reactive than the Group 1 alkali metals, which include lithium.