Which of the following is an example of an alkaline substance?

An alkaline substance is one that has a pH greater than 7, indicating a basic nature. Soap is a prime example of such a substance. It is typically created through the process of saponification, where fats or oils react with an alkali, such as sodium hydroxide or potassium hydroxide. This process results in a product that has a higher pH, making it alkaline.

In contrast, vinegar and citric acid are examples of acidic substances; they possess a pH lower than 7. Vinegar, primarily composed of acetic acid, exhibits sourness and is used in a variety of culinary applications. Citric acid, found in citrus fruits, is a weak organic acid that contributes to the tart flavor of these fruits.

Hydrochloric acid is a strong acid that significantly lowers pH levels and is commonly found in gastric juice within the stomach. Recognizing the properties of these substances helps differentiate between acids and bases, leading to a better understanding of their roles in chemistry and in practical applications, such as in skin care and cleansing products.