The measure of randomness or uncertainty of the substance is known as the entropy of the substance.
Under the standard state, the entropy of one mole of substance is known as its standard molar entropy.
The structure of cyclopropane and propylene is shown in the attached image.
Since, the structure of propylene is an open chain structure thus, possessing high randomness. Whereas the structure of cyclopropane is ring (closed) structure and thus, not that much free to move and has less randomness.
Hence, the structure of propylene will have the higher standard molar entropy.
