Which of the following substances is highly viscous and very slippery?

The substance identified as highly viscous and very slippery is polymer. Polymers are long-chain molecules that can exhibit a range of physical properties, depending on their composition and molecular structure. In wastewater treatment, polymers are often used as flocculants or coagulants to help in the separation of solids from liquids, enhancing the efficiency of the treatment process. Their viscous nature allows them to effectively interact with particulates, forming aggregates that can settle more easily.

In contrast, substances like calcium hypochlorite, calcium oxide, and potassium permanganate are not known for their viscosity or slippery feel. Calcium hypochlorite is primarily used as a disinfectant and has a granular form that does not exhibit slipperiness. Calcium oxide is a dry powder that can be used in various chemical applications, primarily in pH adjustment and does not possess viscosity. Potassium permanganate, while it can be dissolved in water to form a solution, is typically encountered in solid crystal form, which would not be considered slippery or viscous.

Therefore, the properties of the polymer support its classification as highly viscous and slippery, distinguishing it from the other options listed.