The diagram below represents a certain biomolecule - VCE - SSCE Chemistry - Question 3 - 2016 - Paper 1

Erucic acid is classified as monounsaturated because it contains only one double bond in its carbon chain. This means that there are no other double bonds present in the structure, allowing it to maintain a more stable physical form compared to polyunsaturated fats.

Erucic acid is classified as monounsaturated due to the presence of a single carbon-to-carbon double bond in its hydrocarbon chain. This characteristic makes it less saturated with hydrogen atoms compared to saturated fatty acids, which contain no double bonds. As a result, it has specific properties such as a lower melting point and increased fluidity.

The semi-structural formula of methyl erucate can be represented as follows:

$CH_3(CH_2)_{11}CH=CH(CH_2)_{7}COOCH_3$

One environmental advantage of using biodiesel as a fuel is that it is derived from renewable resources such as vegetable oils and animal fats, which can be replenished over time. In comparison, petrodiesel is extracted from fossil fuels that contribute to greenhouse gas emissions when burned, leading to environmental degradation. Thus, biodiesel can potentially reduce carbon dioxide emissions and enhance sustainability.