The most common base is the
hydrogen ion;
hydronium ion;
hydroxide ion;
ammonium ion.
The most common base is the hydroxide ion (OH-). Bases are substances that can accept protons (H+) or donate electron pairs. The hydroxide ion, having a negative charge, readily accepts protons to form water (H2O). It is commonly found in compounds such as sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2).
To determine the most common base from the options you provided, we need to consider their properties. Let's go through each one:
1. Hydrogen ion (H+): This is not a base, but rather a single proton. It is the positively charged ion that results when an acid donates a proton (H+). It is often associated with acidic solutions.
2. Hydronium ion (H3O+): This is the form in which hydrogen ions exist in aqueous solutions. It is formed when a water molecule combines with a hydrogen ion. While it can act as an acid, it is not considered a common base.
3. Hydroxide ion (OH-): This is the common base we are looking for. The hydroxide ion readily accepts protons to form water and is found in many inorganic and organic compounds.
4. Ammonium ion (NH4+): The ammonium ion can behave as an acid since it readily donates a proton (H+). It is not a common base.
Therefore, based on their properties, the correct answer is the hydroxide ion (OH-).