In polymer science, which among the following is classified as an inorganic polymer (i.e., a macromolecule with a backbone containing non-carbon atoms such as Si–O)?

Introduction / Context:
Classifying polymers as organic or inorganic depends on the composition of the main chain (backbone). Most commercial plastics are organic with carbon–carbon or carbon–heteroatom backbones, whereas inorganic polymers include repeating units with non-carbon atoms such as silicon and oxygen in the chain.

Given Data / Assumptions:

• The options list common commercial polymers.
• We identify which one has a non-carbon backbone.
• Terminology: PTFE = polytetrafluoroethylene; PMMA = polymethyl methacrylate.

Concept / Approach:
Silicones (polysiloxanes) possess –Si–O–Si–O– repeating units and are therefore classified as inorganic or organo-inorganic polymers. PTFE, PMMA, and phenolic resins have carbon-based backbones and are grouped as organic polymers despite containing heteroatoms in side groups or crosslinks.

Step-by-Step Solution:
Check each option’s backbone: PTFE → –C–C–; PMMA → –C–C–; Bakelite → crosslinked carbon framework; Silicones → –Si–O–.Select the polymer with a non-carbon backbone: silicones.Confirm others remain organic.

Verification / Alternative check:
Materials texts universally describe polysiloxanes as inorganic/organosilicon polymers due to the siloxane linkage in the chain.

Why Other Options Are Wrong:
Teflon (PTFE): fully organic –C–C– backbone with fluorine substituents.Perspex (PMMA): methacrylate-based carbon chain; organic.Bakelite: phenol–formaldehyde thermoset; carbon framework.

Common Pitfalls:
Confusing the presence of heteroatoms in side groups with heteroatoms in the main chain. Only the backbone composition determines this classification.

Final Answer:
Silicones (polysiloxanes)