Home PYQs UPPSC UPPSC MCQs Prelims 1994 (GS Paper I)

Question

Why does an iron nail float on mercury while it sinks in water?

  1. Due to less chemical interaction of iron with mercury than it is with water
  2. Iron is heavier than water and lighter than mercury
  3. Iron has greater density then water and lesser than, mercury
  4. Mercury is heavier than water

Answer:

Option C: Iron has greater density then water and lesser than, mercury

Detailed Solution:

The correct answer is “Iron has greater density then water and lesser than, mercury”.

An iron nail sinks in water because its density is greater than that of water. However, it floats on mercury because mercury has a much higher density than iron, allowing the nail to float.