Yes, cellulose is indeed held together by hydrogen bonds. Cellulose, a polysaccharide composed of glucose monomers, forms the primary structural component of plant cell walls. Each glucose unit is connected to the next via β-1,4-glycosidic bonds, forming long chains. Within cellulose fibers, individual chains are closely aligned, allowing for the formation of hydrogen bonds between hydroxyl groups of adjacent chains. These hydrogen bonds are crucial for providing cellulose with its high tensile strength and rigidity, essential for the structural integrity of plants. Additionally, the extensive hydrogen bonding contributes to cellulose's insolubility in water and resistance to being broken down by digestive enzymes in most animals, making it an insoluble dietary fiber in human nutrition.

PVC, or Polyvinic Chloride, is known to be inherently flame-retardant due to the chlorine content in its composition. This means that PVC can self-extinguish once the source of ignition is removed. The flame-retardant characteristic of PVC is a significant safety feature, making it a preferred material for numerous applications, including construction and electrical insulation. However, it's crucial to note that while PVC can self-extinguish, under certain conditions or in the presence of strong heat sources, it can still burn and release harmful gases, including hydrochloric acid. Therefore, while PVC's self-extinguishing properties enhance its safety profile, caution should still be exercised during its use, especially in fire-prone areas.

PVC, or Polyvinic Chloride, is known to be inherently flame-retardant due to the chlorine content in its composition. This means that PVC can self-extinguish once the source of ignition is removed. The flame-retardant characteristic of PVC is a significant safety feature, making it a preferred material for numerous applications, including construction and electrical insulation. However, it's crucial to note that while PVC can self-extinguish, under certain conditions or in the presence of strong heat sources, it can still burn and release harmful gases, including hydrochloric acid. Therefore, while PVC's self-extinguishing properties enhance its safety profile, caution should still be exercised during its use, especially in fire-prone areas.

Polyethylene, a thermoplastic polymer, is known for its excellent chemical resistance. It is generally considered non-reactive and unresponsive to many solvents at room temperature, which makes it a popular choice for various applications, such as packaging and manufacturing. However, when it comes to its solubility in chloroform, the story is a bit more complex. Chloroform (CHCl3) is a good solvent for many organic compounds due to its polar nature and ability to interact with various functional groups. Yet, polyethylene lacks specific functional groups that would allow it to form strong interactions with chloroform. Under normal conditions, polyethylene does not dissolve in chloroform. However, under elevated temperatures and pressures, some types of polyethylene can swell or partially dissolve in chloroform. High molecular weight polyethylene is less likely to dissolve due to its tightly packed structure, while low molecular weight polyethylene might show more interaction with chloroform. In practical terms, if you need to work with polyethylene in a chloroform environment, it is advisable to use high-density polyethylene (HDPE) or cross-linked polyethylene, as these variants offer better resistance to solvent attack.