2000 General Studies, all questions

UPSC Prelims 2000 · General Studies

Question 111: Science and Technology

Aluminium surfaces are often “anodized”. This means the deposition of a layer of

achromium oxide
baluminium oxide
cnickel oxide
dzinc oxide

AnswerThe answer is (b).

Anodizing is an electrolytic process in which the aluminium object is made the anode in an acid bath. Oxygen released there combines with the metal to build a thicker, harder layer of aluminium oxide on the surface. This layer resists corrosion and wear, and it can be dyed. So the layer deposited is aluminium oxide.

Why each option is right or wrong
  • (a) Chromium oxide is not what anodizing builds on aluminium.
  • (b) Right: anodizing builds a layer of aluminium oxide.
  • (c) Nickel oxide is not what anodizing builds on aluminium.
  • (d) Zinc oxide is not what anodizing builds on aluminium.

Explanation: written by UPSC Grade, not by UPSC.

Practise this paper timedPrevious questionNext question

Source: UPSC, Civil Services (Preliminary) Examination 2000, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.