What is a characteristic of bases in terms of pH?

• A. They are corrosive and slippery.
• B. They are always neutral.
• C. They cause immediate corrosion.
• D. They are less reactive than acids.

Answer: (A)

Bases are characterized by their ability to increase the pH of a solution, typically resulting in a higher pH value than 7. This increase indicates that the solution is basic or alkaline. One of the hallmark features of bases is that they are generally corrosive and can feel slippery, which is due to their chemical nature. This slippery feel is a result of the way bases interact with fats and oils, saponifying them and creating a slippery texture. This characteristic is often observed when handling substances like sodium hydroxide or potassium hydroxide.

In contrast to this, being always neutral or causing immediate corrosion would not accurately describe all bases. Bases do not always present themselves as being neutral; rather, they are defined by their basicity, which is distinctly above neutral pH levels. While some bases are indeed corrosive, the immediate corrosion aspect varies widely among different bases. Lastly, bases can be more reactive than acids in certain contexts, so classifying them as less reactive is misleading. Therefore, the correct answer highlights an essential feature of bases relevant to their chemical properties and behavior.