Question

A constant pressure air thermometer gave a reading of 47.5 units of volume when immersed in ice cold water, and 67 units in a boiling liquids. The boiling point of the liquid will be

• A. 135°C
• B. 125°C
• C. 112°C
• D. 100°C

Answer 1

Answer: (C)

112°C

Answer 2

Initial volume $V_{1} = 47.5$ units

Temperature of ice cold water $T_{1} = 0{^\circ}C = 273K$

Final volume of $V_{2} = 67$ units

Applying Charle’s law, we have $\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}$

(where temperature $T_{2}$ is the boiling point)

or $T_{2} = \frac{V_{2}}{V_{1}} \times T_{1} = \frac{67 \times 273}{47.5} = 385K = 112{^\circ}C$