UPSC Prelims 2021 GS Paper I · Q74 of 98 General Science easy

Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

  1. (a) Low-density polyethylene
  2. (b) Polycarbonate ✓ UPSC's answer
  3. (c) Polyethylene terephthalate
  4. (d) Polyvinyl chloride

Why the answer is (b)

• Bisphenol A is a monomer that reacts with phosgene to make polycarbonate, the hard clear plastic used in water bottles, baby bottles, CDs and eyewear; it is also used in epoxy can linings — option (b).

• Concern arises because BPA can leach out and act as an endocrine disruptor mimicking oestrogen, leading to 'BPA-free' products and bans on BPA baby bottles in India (BIS) and the EU.

• LDPE (a) is made from ethylene, PET (c) from terephthalic acid and ethylene glycol, and PVC (d) from vinyl chloride — none uses BPA as a building block.

• Hence option (b).

Why the other options are wrong

(a) Low-density polyethylene
LDPE is made from ethylene, not BPA.
(c) Polyethylene terephthalate
PET is made from terephthalic acid and ethylene glycol.
(d) Polyvinyl chloride
PVC is made from vinyl chloride.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2021, held on 10 October 2021. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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