UPSC Prelims 2000 · General Studies
Question 109: Science and Technology
Which one of the following materials is very hard and very ductile?
AnswerThe answer is (d).
Nichrome, an alloy of nickel and chromium, is tough, hard-wearing and ductile, and is drawn into wire for heating elements. Carborundum (silicon carbide) is very hard but brittle, and cast iron is hard but brittle. Tungsten is hard and has a very high melting point, but it is brittle unless specially worked into wire.
Why each option is right or wrong
- (a) Carborundum is very hard but brittle, not ductile.
- (b) Tungsten is hard and drawn into filaments, but is brittle unless specially worked; the key prefers nichrome.
- (c) Cast iron is hard but brittle, not ductile.
- (d) Right: nichrome is a hard, tough alloy that can be drawn into wire.
Worth knowing: Tungsten is also very hard and, once drawn into wire, very ductile, so (b) is arguable.
Explanation: written by UPSC Grade, not by UPSC.
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.