Answer is: region A (from picture below).
Region A contains alkaline and earth alkaline elements (metals). This elements have lowest ionizations energy and easy remove valence electrons (alkaline metals one electron and earth alkaline metals two electrons). When element lose electrons, oxidation number of element grows (oxidation process).
The answer is buffers.
Chemicals called buffers are those that can combine with H⁺ when hydrogen ions are in excess, and release H⁺ when hydrogen ion levels are low. the function of these chemicals is to minimize changes in pH.
Buffers are the substances that resist change in its pH on addition of small volume of acid and base.
Answer:
The Atomic Number
Explanation:
The X would be the Atomic Number or amount of protons sorrounding the nucleus of that atom.