UPSC Prelims 2012 · GS Paper I
Question 14: Science and Technology
Graphene is frequently in news recently. What is its importance?
- 1.It is a two-dimensional material and has good electrical conductivity.
- 2.It is one of the thinnest but strongest materials tested so far.
- 3.It is entirely made of silicon and has high optical transparency.
- 4.It can be used as 'conducting electrodes' required for touch screens, LCDs and organic LEDs.
Which of the statements given above are correct?
AnswerUPSC’s answer is (c).
Graphene is a single layer of carbon atoms arranged in a honeycomb lattice, a two-dimensional material. It conducts electricity very well, is among the thinnest and strongest materials tested, and is nearly transparent, so it is being developed as a conducting electrode for touch screens, LCDs and organic LEDs. The wrong statement says it is made of silicon; graphene is pure carbon, like graphite and diamond.
- 1. Graphene is a one-atom-thick sheet and a very good conductor.
- 2. It is extremely thin yet among the strongest materials tested.
- 3. Graphene is made entirely of carbon, not silicon.
- 4. Being conductive and transparent, it suits electrodes for touch screens, LCDs and OLEDs.
How you could have got this
- If you were sure statement 3 is not correct, (b) and (d) go: each of them includes 3.
What you needed to know: Graphene is made entirely of carbon, not silicon.
- Then, if you were sure statement 4 is correct, (a) goes: it leaves 4 out.
What you needed to know: Being conductive and transparent, it suits electrodes for touch screens, LCDs and OLEDs.
Only (c) is left. You didn’t need statements 1 or 2.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Incomplete: its use as conducting electrodes in screens and LEDs is also correct.
- (b) Wrong: statement 3 is false, as graphene is carbon, not silicon.
- (c) Correct: statements 1, 2 and 4 hold; graphene is carbon.
- (d) Wrong: it includes statement 3, which wrongly says graphene is made of silicon.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper I, Series A. The paper on upsc.gov.in.