Which one of the following correctly defines the state of glass?

Glass is scientifically defined as a non-crystalline, amorphous state of matter that exhibits a glass transition [3]. It is most commonly described as a supercooled liquid because it is formed by cooling a liquid fast enough to avoid crystallization, thereby retaining the disordered molecular arrangement of the liquid state while gaining the mechanical rigidity of a solid [2]. Unlike crystalline solids, which have a long-range ordered structure and a sharp melting point, glass is a metastable phase that lacks such order. While it appears solid on short timescales, it is technically a nonequilibrium state that continuously relaxes toward the liquid state [1]. This unique nature, where a liquid's viscosity increases to the point of rigidity without a first-order phase transition into a crystal, justifies its classification as a supercooled liquid in many scientific contexts.

Sources

1. [1] https://www.sciencedirect.com/science/article/abs/pii/S0022309317302685
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC10875679/
3. [2] https://en.wikipedia.org/wiki/Glass_transition