Final answer:
The statement "double bonds are less flexible" is true, because of restricted rotation due to the presence of both a σ bond and a π bond. This characteristic affects the physical properties of compounds containing double bonds, such as their melting points.
Step-by-step explanation:
When atoms are connected by a double bond, there are two shared pairs of electrons between them, consisting of one σ bond and one π bond. The σ bond is formed by the end-to-end overlap of orbitals, resulting in a stronger and more direct connection, whereas the π bond occurs due to the sideways overlap of parallel p-orbitals and is generally weaker than the σ bond. Additionally, the presence of the π bond in a double bond restricts rotation, leading to a decrease in flexibility in comparison to single-bonded atoms which only contain a σ bond and allow free rotation.
Unsaturated fats and trans fats have some double-bonded carbon atoms, and this affects their physical properties, such as melting points. In contrast, saturated fats do not have double bonds and tend to be solids at room temperature because of their straight chain structure which allows tight packing.
A triple bond is also less flexible due to the presence of two π bonds. Despite the fact that a triple bond allows some rotation as one π bond breaks and another form, its linear geometry means that this rotation is less significant, especially compared to the free rotation seen around a single bond.