Nylon-$6, 6$ is not a ...... .

The biodegradable polymer is

In the trinitrocellulose,each glucose unit contains how many $-OH$ groups?

Which of the following is a common use of $HDPE$ (High-Density Polyethylene)?

Which of the following statements are correct?
$(1)$ Biodegradable polymers can be converted into essential life substances after degradation.
$(2)$ Non-biodegradable polymers are active towards environmental processes.
$(3)$ Non-biodegradable polymers can be converted into essential life substances.
$(4)$ $PHBV$ is degraded by bacteria under environmental conditions.

Which polymer is used as a lubricant and an insulator?