Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?
- A.Low-density polyethylene
- B.Polycarbonate
- C.Polyethylene terephthalate
- D.Polyvinyl chloride
Correct answer
Explanation
The correct answer is B, Polycarbonate. Bisphenol A is the main building block from which polycarbonate plastic is made. Polycarbonate is a hard, clear and shatter-resistant plastic once widely used for reusable water bottles, baby feeding bottles, food containers, CDs and spectacle lenses. BPA is also used in the epoxy resins that line food and drink cans. The concern is that BPA can leach out, especially when the plastic is heated or scratched, and it acts as an endocrine disruptor because it mimics the hormone oestrogen. For this reason many countries, including India, have banned BPA in baby feeding bottles. Option A is wrong because low-density polyethylene is made from ethylene alone and is used for carry bags and films. Option C is wrong because PET, used for soft-drink bottles, is made from ethylene glycol and terephthalic acid. Option D is wrong because PVC is made from vinyl chloride; its worry is phthalate plasticisers, not BPA. Exam tip: BPA goes with polycarbonate and epoxy can linings; phthalates go with PVC.
Practice Questions
View allWhich one of the following is not used as fertilizer?
- A.Ammonium nitrate
- B.Ammonium sulphide
- C.Ammonium phosphate
- D.Ammonium sulphate
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Ammonium sulphide is an unstable, foul-smelling compound that breaks down to release ammonia and toxic hydrogen sulphide, so it is not used as a fertiliser.
Read the full explanation →The focal length of the objective lens of a telescope is 50 cm. If the magnification of the telescope is 25, then the focal length of the eye-piece is
- A.12.5 cm
- B.5 cm
- C.2 cm
- D.10 cm
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For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.
Read the full explanation →The major source of vitamins and minerals for vegetarians is
- A.black gram and wheat.
- B.rice and mustard.
- C.vegetables and fruits.
- D.soya bean and milk.
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Vegetables and fruits supply most of the vitamins and minerals in a vegetarian diet, which is why they are called protective foods.
Read the full explanation →Which one of the following compounds is used in black and white photography?
- A.AgF
- B.AgBr
- C.AgCl
- D.Ag2SO4
Show answer
Silver bromide is the light-sensitive compound coated on black and white photographic film and paper, because light breaks it down into tiny grains of silver metal.
Read the full explanation →Which one of the following statements about speed and velocity is correct?
- A.Speed and velocity both are vector quantities.
- B.Speed and velocity both are scalar quantities.
- C.Speed is vector quantity and velocity is scalar quantity.
- D.Speed is scalar quantity and velocity is vector quantity.
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Speed tells only how fast a body moves, while velocity also tells the direction of motion, and a quantity with both magnitude and direction is a vector.
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