All the following belong to the same family EXCEPT

Analyze the question: We need the one substance that does NOT belong to the same family as the others. The options are B (nylon), C (perspex), D (polyethene) and E (polystyrene), which are all polymers, plus A (glycerol).

Concept: Polymers are large molecules built from many repeating monomer units. Synthetic polymers include:

• Nylon: a polyamide, formed by condensation polymerisation
• Perspex (polymethyl methacrylate): an addition polymer
• Polyethene: an addition polymer of ethene
• Polystyrene: an addition polymer of styrene (phenylethene)

Glycerol (propane-1,2,3-triol, CH₂OH-CHOH-CH₂OH) is a small molecule. It is a trihydric alcohol, and it is not a polymer. It is used as a raw material in making soap and explosives (nitroglycerine), but it is not a macromolecule.

Step by step:

1. Check each option for polymer status.
2. Nylon, perspex, polyethene and polystyrene are all synthetic polymers (plastics/fibres).
3. Glycerol is an alkanol (a polyhydric alcohol), so it is the odd one out.

Note on the options: "Perspex polyethene" in option C looks like a typing slip in the question bank. Perspex and polyethene are separate polymers, but either way option C is a polymer and still fits with the others.

Answer: A. glycerol

Tip: In "odd one out" questions, first sort the options into classes. Here, four are polymers (large, repeating units) and one is a simple alcohol. Names starting with "poly-" or ending in plastics/fibres (nylon, perspex, terylene) are usually polymers.