2005 General Studies, all questions
UPSC Prelims 2005 · General Studies
Question 101: Science and Technology
Which one of the following is the correct sequence of the given substances in the decreasing order of their densities?
aSteel > Mercury > Gold
bGold > Mercury > Steel
cSteel > Gold > Mercury
dGold > Steel > Mercury
AnswerThe answer is (b).
Densities in g/cm³ are about 19.3 for gold, 13.6 for mercury and 7.8 for steel. So the decreasing order is gold, mercury, steel. Mercury is the densest common liquid, which is why steel floats on it. To remember the scale, a litre of gold weighs about 19 kg, a litre of mercury about 13.6 kg and a litre of steel about 7.8 kg.
Why each option is right or wrong
- (a) Puts steel above mercury and gold; steel is the least dense.
- (b) Correct: gold > mercury > steel.
- (c) Puts steel above gold and mercury; steel is the least dense.
- (d) Puts steel above mercury; mercury is denser than steel.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2005, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.