Saturation concentration refers to the highest concentration of a substance that can exist in a solution in equilibrium with its solid or gaseous form. A saturation concentration less than 5 but greater than 2 is a relatively broad range, and many different chemicals could fall within this range depending on the conditions of the solution.
Examples of chemicals with saturation concentration less than 5 but greater than 2 include:
Calcium carbonate, which has a saturation concentration of around 3.5 g/L at room temperature and normal pressure
Iron(III) hydroxide, which has a saturation concentration of around 3.5 g/L at room temperature and normal pressure
Potassium chloride, which has a saturation concentration of around 3.5 g/L at room temperature and normal pressure
Ammonium chloride, which has a saturation concentration of around 2.5 g/L at room temperature and normal pressure
Sodium sulfate, which has a saturation concentration of around 3.5 g/L at room temperature and normal pressure
It's important to note that these are just examples, the saturation concentration of a chemical can vary depending on temperature, pressure, and other factors.