Q. 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) $135℃$
B) $125℃$
C) $112℃$
D) $100℃$
Explanation
(c) Initial volume $V_{1} = 47.5$ units
Temperature of ice cold water $T_{1} = 0℃ = 273\ K$
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)
$or\ T_{2} = \frac{V_{2}}{V_{1}} \times T_{1} = \frac{67 \times 273}{47.5} = 385\ K = 112℃$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.