Which of the following terms refers to solutions that have a high concentration of hydroxide ions?

The term that refers to solutions with a high concentration of hydroxide ions is indeed basic solutions. Basic solutions, or alkaline solutions, are characterized by a pH greater than 7. In these solutions, the concentration of hydroxide ions (OH^-) surpasses that of hydrogen ions (H^+). This relationship results in a higher pH value, indicating the basic nature of the solution.

The presence of hydroxide ions is primarily responsible for the properties associated with basic solutions, such as their ability to react with acids to neutralize them, forming water and salt in the process. Basic solutions are often found in compounds such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), which dissociate in water to increase the concentration of hydroxide ions. Understanding the characteristics of basic solutions is crucial in various chemical contexts, especially in acid-base reactions and pH calculations.