Borax is one of the most common compounds of which element?

Borax is a compound that is primarily a source of the element boron, which is why it is correctly associated with boron in this context. The chemical formula for borax is Na2B4O7·10H2O, indicating that it contains boron atoms bonded with oxygen, sodium, and water molecules. Boron is a metalloid that plays a significant role in various applications, including glass and ceramics production, as well as in agriculture as a micronutrient.

Understanding borax's composition highlights its relationship with boron, making it a common and significant boron compound in both industrial and household uses. The other elements listed do not form borax or play a primary role in its chemical identity.