Final answer:
Petrodiesel is hygroscopic and absorbs moisture from the atmosphere, while biodiesel has lower hygroscopic properties and absorbs less moisture. This is due to the different chemical compositions of the two fuels.
Step-by-step explanation:
Petrodiesel and biodiesel differ in their hygroscopic properties. Petrodiesel is hygroscopic, which means it has a tendency to absorb moisture from the atmosphere. This can lead to issues such as microbial growth and fuel degradation. On the other hand, biodiesel has lower hygroscopic properties, meaning it absorbs less moisture from the atmosphere. This is due to the different chemical compositions of petrodiesel and biodiesel. Petrodiesel is primarily composed of hydrocarbons, while biodiesel is made from vegetable oils or animal fats through a process called transesterification.