Polyamides are a type of synthetic polymers that are formed by the condensation reaction between a dicarboxylic acid and a diamine. They have repeating amide groups (-CONH-) in their polymer chain. Polyamides are known for their high strength, durability, and resistance to wear and tear. They are commonly used in the production of textiles, carpets, and engineering plastics.

Nylon-66 is a type of polyamide that is formed by the condensation reaction between adipic acid (a dicarboxylic acid with 6 carbon atoms) and hexamethylenediamine (a diamine with 6 carbon atoms). The name "Nylon-66" comes from the fact that both the dicarboxylic acid and diamine have 6 carbon atoms.

- The correct answer to the given question is option 'A', Nylon-66.
- Nylon-66 is a polyamide, which means it is a synthetic polymer with repeating amide groups in its polymer chain.
- Nylon-66 is formed by the condensation reaction between adipic acid and hexamethylenediamine.
- It is known for its high strength, durability, and resistance to wear and tear.
- Nylon-66 is commonly used in the production of textiles, carpets, and engineering plastics.
- It is also used in the manufacturing of various products such as ropes, fishing nets, automotive parts, and electrical insulation.
- Teflon, option 'B', is not a polyamide. It is a brand name for polytetrafluoroethylene (PTFE), which is a type of polymer known for its non-stick properties.
- Bakelite, option 'C', is not a polyamide. It is a thermosetting plastic made from phenol formaldehyde resin and is known for its electrical insulating properties.
- Terylene, option 'D', is not a polyamide. It is a brand name for a type of polyester fiber that is commonly used in the production of clothing and textiles.

In conclusion, Nylon-66 is the correct answer as it is a polyamide formed by the condensation reaction between adipic acid and hexamethylenediamine. It is widely used in various industries for its strength, durability, and resistance properties.