There are many substances that have a pH of 1. Some examples of substances that have a pH of 1 include: Hydrochloric acid: Hydrochloric acid is a strong acid that is commonly used in a variety of industrial and laboratory settings. It is also found naturally in the stomach, where it helps to digest food. Hydrochloric acid has a pH of 1. Lemon juice: Lemon juice is a common ingredient in cooking and is known for its sour taste. It is made up primarily of citric acid, which gives it a pH of around 2. Battery acid: Battery acid is a strong acid that is used in lead-acid batteries, such as those found in cars. It has a pH of around 1. Tomato juice: Tomato juice is a common beverage that is made from tomatoes and has a pH of around 4.5. However, some types of tomato juice, such as those that are highly concentrated or have been subjected to certain processing methods, may have a pH of 1 or lower. It's important to note that the pH scale is logarithmic, meaning that each increment on the scale represents a tenfold difference in acidity or basicity. For example, a solution with a pH of 4 is ten times more acidic than a solution with a pH of 5, and a solution with a pH of 3 is 100 times more acidic than a solution with a pH of 5.