Which of the following statement is not true for detergent molecule?

It is sodium salt of fatty acid

The correct answer is option 4. It is sodium salt of fatty acid.

Detergent molecules are a type of surfactant, which stands for surface-active agent. Their structure typically consists of a polar, hydrophilic (water-attracting) head and a non-polar, hydrophobic (water-repelling) tail. This dual nature allows detergents to interact with both water and oily substances, making them effective for cleaning.

Let us break down the options:

1. It is not easily biodegradable: This statement is often true for many synthetic detergents, especially those containing long hydrocarbon chains. These can persist in the environment for long periods before breaking down, causing potential harm. However, there are also biodegradable detergents available, so this statement is not universally true for all detergents

2. It is a surface-active agent: This statement is true. Detergents lower the surface tension of water, allowing it to spread more easily and penetrate into fabrics or other materials to aid in cleaning.

3. It has a non-polar organic part and a polar non-organic part: This statement accurately describes the structure of detergent molecules. The non-polar organic part is typically a long hydrocarbon chain, while the polar part can be a variety of functional groups like sulfates, sulfonates, or quaternary ammonium ions.

4. It is sodium salt of fatty acid: This statement is not universally true for all detergents. While some detergents may include sodium salts of fatty acids in their composition, not all detergents are based on this specific chemical structure. As mentioned earlier, detergents have diverse structures with varying polar and non-polar components.

So, option 4 is the statement that is not universally true for all detergent molecules.