Jar test results are expressed in:

• A. Grams per liter
• B. Milligrams per liter
• C. Parts per billion
• D. Percentage

Answer: (B)

Jar test results are primarily expressed in milligrams per liter (mg/L) because this unit is commonly used to measure the concentration of chemicals or particles in water samples during testing. The jar test is a laboratory procedure used to evaluate the effectiveness of coagulants in treating water, specifically in determining the optimal dosages for achieving desired water quality parameters such as turbidity reduction.

Milligrams per liter is particularly suitable for representing concentrations of coagulants, residual chemicals, or contaminants that are present in trace amounts within the water. This unit provides the precision needed for analyzing how effective a given treatment is by quantifying the chemical constituents in minute amounts, which is critical in water treatment scenarios.

While grams per liter, parts per billion, and percentage could theoretically be relevant in other contexts, they are not the standard for jar test results in water treatment practices. Grams per liter would imply a much higher concentration than typically seen in water treatment applications, parts per billion represents an even smaller concentration which is usually irrelevant in the context of jar testing, and percentage expressions do not effectively convey the necessary precision for chemical concentrations in this setting. Therefore, milligrams per liter remains the most appropriate and widely accepted unit for jar test results.