2008 General Studies, all questions

UPSC Prelims 2008 · General Studies

Question 113: Science and Technology

What are Rubies and Sapphires chemically known as?

aSilicon dioxide
bAluminium oxide
cLead tetroxide
dBoron nitride

AnswerThe answer is (b).

Rubies and sapphires are both varieties of corundum, which is aluminium oxide (Al2O3). Ruby is red because of traces of chromium, and sapphires are usually blue because of traces of iron and titanium. Corundum is very hard, rating 9 on the Mohs scale. Silicon dioxide is quartz or sand, lead tetroxide is red lead and boron nitride is an industrial ceramic.

Why each option is right or wrong
  • (a) Silicon dioxide makes quartz and sand.
  • (b) Aluminium oxide (corundum) is the chemical.
  • (c) Lead tetroxide is red lead, a pigment.
  • (d) Boron nitride is a synthetic ceramic.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2008, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.