Give reason: use of synthetic detergents causes pollution of water.

Synthetic detergents consist of calcium and magnesium salts which are soluble in water. They play a significant role in increasing water pollution as they are non-biodegradable. They are not easily decomposed by the microorganisms. As detergents are basic (has high pH), they increase the basicity of water and soil, thus affecting the aquatic life also. Detergents also assist the rapid growth of algae and weeds in the water, thus depletes the oxygen content of water. Therefore, the use of synthetic detergents is harmful and causes water pollution.