Which of the following is a common laboratory alkali?

Sodium hydroxide is recognized as a common laboratory alkali because it is a strong base that dissolves in water to produce hydroxide ions (OH⁻). This characteristic gives sodium hydroxide its alkaline properties, making it useful in various laboratory applications, including titrations and neutralization reactions. It is also often used for pH adjustments and as a cleaning agent due to its ability to react with acids to form water and a salt.

In contrast, sulfuric acid, hydrochloric acid, and nitric acid are all strong acids. They release hydrogen ions (H⁺) in solution, leading to an acidic environment rather than an alkaline one. Thus, they do not fulfill the criteria for being classified as alkalis. Understanding the properties of bases and acids is crucial for recognizing their applications and roles in chemical reactions within a laboratory setting.