If you mean what group of elements react the most, the answer is the alkali metals and the halogens because they both only either need to gain or lose one electron. If you mean the most reactive element, it would be fluorine because it has the most electronegativity.
If you would’ve attached a picture I’m sure it would’ve been a lot easier.
Answer:
-Growth of plants on the rock.
-Temperature and pressure changes in nature.
-Freezing and thawing of water in cracks of the rock.
-Formation of salt crystals within the rock.
-Burrowing by animals.
those are some factors I know
hope this helped you
<u>Answer:</u> The balanced half reaction is written below.
<u>Explanation:</u>
Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

When oxygen gas is reduced to oxide ions, the number of electron transferred are 2
The chemical equation for the reduction of oxygen gas to oxide ions follows:

Hence, the balanced half reaction is written above.