With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements : 1. Its fibres can be blended with wool and cotton fibres to reinforce their properties. 2. Containers made of it can be used to store any alcoholic beverage. 3. Bottles made of it can be recycled into other products. 4. Articles made of it can be easily disposed of by incineration without causing greenhouse gas emissions. Which of the statements given above are correct?
- A.1 and 3
- B.2 and 4
- C.1 and 4
- D.2 and 3
Correct answer
Explanation
The correct answer is A, 1 and 3. PET fibre (polyester) is blended with wool and cotton, and PET bottles are widely recycled into new products.
Polyethylene terephthalate is a polyester made from ethylene glycol and terephthalic acid. As a fibre it is sold as polyester or terylene, and blends such as terry-cotton and terry-wool combine its strength and crease resistance with the comfort of natural fibres. Used PET bottles are washed, flaked and remade into fibre for clothes and carpets, sheets, straps and new bottles; PET carries the resin code 1.
Statement 2 is wrong because PET is not suited to every alcoholic drink: it lets small amounts of oxygen and carbon dioxide pass through its walls, which spoils drinks such as wine and beer over time, so many of them are kept in glass or cans. Statement 4 is wrong because burning PET, a carbon-based plastic, releases carbon dioxide, a greenhouse gas. So B, C and D, which include 2 or 4, are wrong.
Exam tip: PET = polyester/terylene, resin code 1, recyclable; burning it emits CO2.
Practice Questions
View allConsider the following pairs :
Objects in space : Description
1. Cepheids : Giant clouds of dust and gas in space
2. Nebulae : Stars which brighten and dim periodically
3. Pulsars : Neutron stars that are formed when massive stars run out of fuel and collapse
How many of the above pairs are correctly matched?
- A.Only one
- B.Only two
- C.All three
- D.None
Show answer
Only pair 3 is right; the descriptions of Cepheids and nebulae have been swapped. Cepheid variables are pulsating stars that brighten and dim on a regular cycle.
Read the full explanation →The terms 'Event Horizon', 'Singularity', 'String Theory' and 'Standard Model' are sometimes seen in the news in the context of
- A.Observation and understanding of the Universe
- B.Study of the solar and the lunar eclipses
- C.Placing satellites in the orbit of the Earth
- D.Origin and evolution of living organisms on the Earth
Show answer
All four terms come from physics and cosmology, the study of how the universe and its matter work. An event horizon is the boundary around a black hole beyond which nothing, not even light, can escape.
Read the full explanation →A charged particle moves through a magnetic field B with a velocity v. Which one of the following statements is true for the force (F) experienced by the particle?
- A.F is maximum when v and B are parallel to each other.
- B.F is maximum when v and B are anti-parallel to each other.
- C.F is maximum when v and B are perpendicular to each other.
- D.The force F is independent of the angle between v and B.
Show answer
The magnetic force depends on the sine of the angle between velocity and field, and sin 90° is the largest value.
Read the full explanation →In Sun-Earth system, the Sun, the Earth and the Lagrange point L4 form :
- A.an isosceles triangle
- B.an equilateral triangle
- C.a straight line
- D.a scalene triangle
Show answer
L4 lies on Earth's orbit 60° ahead of the Earth, so it is as far from the Sun as from the Earth.
Read the full explanation →Which one of the following is the most characteristic property of an element?
- A.Density
- B.Boiling point
- C.Mass number
- D.Atomic number
Show answer
The number of protons in the nucleus defines an element, and no two elements share it. The atomic number (Z) is the number of protons in an atom's nucleus, and in a neutral atom it also equals the number of electrons, which decide chemical behaviour.
Read the full explanation →