Thermometry: Why is mercury commonly used as a thermometric liquid instead of water? Select the most appropriate combined reason relevant to laboratory/clinical thermometers. Choose the correct option.
IIT JEE
Physics
Difficulty: Easy
Choose an option
-
AIt wets glass and evaporates easily
-
BIt expands uniformly, does not wet glass, and has a high boiling point giving a wide measurable range
-
CIt has an extremely low freezing point (below −100°C)
-
DIt is colorless and transparent like water
Answer
Correct Answer: It expands uniformly, does not wet glass, and has a high boiling point giving a wide measurable range
Explanation
ReasonsMercury shows near-uniform thermal expansion, does not wet glass (clear meniscus/readings), and boils at ~357°C enabling a wide upper range. It is also opaque and shiny for easy visibility.
NoteAlthough mercury freezes at about −39°C (higher than alcohols), its other properties make it favorable for many thermometers.
Final AnswerIt expands uniformly, does not wet glass, and has a high boiling point giving a wide measurable range