Question

The thermometer in the diagram has no scale. Where must the bulb be placed so that $ {0^0}C $ can be marked on the stem?

(A) In freezer
(B) In pure boiling water
(C) In pure cold water
(D) In pure melting ice

Answer 1

Hint: Freezer usually has a temperature of $ - {18^0}C $ . Water is considered to be boiling when the vapour pressure of water equals the atmospheric pressure, at sea level to make the vapour pressure and atmospheric pressure equal a temperature of $ {100^0}C $ is needed.

Complete Step By Step Answer:
Because ice melts at $ {0^0}C $ it will be the perfect choice for dipping the thermometer to ensure $ {0^0}C $ on the scale. Normally, at any temperature less than $ {0^0}C $ water will be present only in solid state and at $ {0^0}C $ both solid and liquid state coexist. For any rise from this temperature the ice will be melted and only liquid form will exist.
In a freezer the temperature can fall below zero degrees so it is not possible to measure $ {0^0}C $ using a thermometer without a scale.
 In pure boiling water the temperature will be $ {100^0}C $ .
In pure cold water the temperature can be anywhere above $ {0^0}C $ so exact measurement is not possible.
Option (D) is the correct answer.

Note:
Water has a unique property called anomalous expansion of water. Due to this property when the temperature falls down from $ {4^0}C $ to $ {0^0}C $ its density increases and expands. So water is most dense when the temperature is $ {4^0}C $ . It behaves like any other substance until it reaches $ {4^0}C $ , this anomaly is only observed in case of water and no other liquid displays this property. Generally all other materials contract as temperature decreases and expands when temperature is raised.