The monomer/monomers used for the synthesis of Nylon 6 is/are
- A.hexamethylenediamine and adipic acid
- B.caprolactam
- C.urea and formaldehyde
- D.phenol and formaldehyde
Correct answer
Explanation
The correct answer is B, caprolactam. Nylon 6 is made from a single monomer, caprolactam, whose ring opens on heating and joins up into long polyamide chains.
Caprolactam has six carbon atoms in its ring, which gives Nylon 6 its name. Because one monomer supplies both the amine and the acid ends of the chain, its polymerisation is a ring-opening reaction. Nylon 6 is used for tyre cords, fabrics and ropes. Its relative Nylon 6,6 is a condensation polymer of two monomers, each with six carbon atoms, and water is given off as they link.
A, hexamethylenediamine and adipic acid, are the two monomers of Nylon 6,6, not Nylon 6. C, urea and formaldehyde, form urea-formaldehyde resin, used in unbreakable cups and electrical switches. D, phenol and formaldehyde, form Bakelite, a thermosetting plastic used for electrical fittings and handles of utensils.
Exam tip: Nylon 6 from caprolactam alone; Nylon 6,6 from hexamethylenediamine plus adipic acid; Bakelite from phenol plus formaldehyde.
Practice Questions
View allA negative work is done when an applied force F and the corresponding displacement S are
- A.perpendicular to each other.
- B.parallel to each other.
- C.anti-parallel to each other.
- D.equal in magnitude.
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Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.
Read the full explanation →Which one of the following statements about a satellite orbiting around the Earth is correct ?
- A.Satellite is kept in orbit by remote control from ground station.
- B.Satellite is kept in orbit by retro-rocket and solar energy keeps it moving around the Earth.
- C.Satellite requires energy from solar panels and solid fuels for orbiting.
- D.Satellite does not require any energy for orbiting.
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Once a satellite is placed in orbit with the right speed, the Earth's gravity keeps it going round without any engine.
Read the full explanation →Which one of the following is not a conservative force ?
- A.Frictional force
- B.Electric force
- C.Gravitational force
- D.Spring force
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Friction is a non-conservative force because the work it does depends on the path taken and the energy it removes is lost as heat.
Read the full explanation →A microphone converts
- A.electrical signals to sound waves
- B.sound waves to electrical signals
- C.microwaves to sound waves
- D.sound waves to microwaves
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A microphone is a transducer that changes the pressure variations of sound into a matching electrical signal. In a common dynamic microphone, sound waves make a thin diaphragm vibrate.
Read the full explanation →When a light ray passes through from air to water with a non-zero angle the ray will be
- A.bending towards the normal
- B.bending away from the normal
- C.propagating in straight line
- D.reflected towards the opposite direction
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Light slows down when it enters water from air, so a ray that strikes the surface at an angle bends towards the normal.
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