Strontium, Calcium, Magnesium
Strontium is the most reactive of the three element because of this, it does not exist free in nature but rather exist in combination with other elements in various compounds such as strontianite. Calcium is more reactive than magnesium because it is larger than magnesium and thus, it is more electropositive in nature.
Answer: The correct answer is strontium, calcium, magnesium.
Explanation:
Reactivity is defined as the tendency of an atom to loose or gain electrons.
The reactivity of metal decreases as we move from left to right in a period and increases as we move from top to bottom in a group.
The given elements are metals and they belong to group 2 of the periodic table.
Calcium belongs to Period 4 of the periodic table, magnesium belongs to Period 3 of the periodic table and strontium belongs to Period 5 of the periodic table.
Strontium will be more reactive than calcium and it will be more reactive than magnesium.
Order of reactivity of metals follows:
[tex]\text{Strontium}>\text{Calcium}>\text{Magnesium}[/tex]
Hence, the correct answer is strontium, calcium, magnesium.
