Q122 / 180 · AIIMS 2001 · Physics
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 liquid. The boiling point of the liquid, is
- A$125^{\circ} \mathrm{C}$
- B$100^{\circ} \mathrm{C}$
- C$135^{\circ} \mathrm{C}$
- Correct answerD$112^{\circ} \mathrm{C}$.
Solution
A constant pressure air-thermometer is based on the law
$$
\frac{V_1}{T_1}=\frac{V_2}{T_2} \Rightarrow \frac{T_2}{V_1}=\frac{V_2}{V_1}
$$
Here it is given that $V_1=47.5$
$$
\begin{aligned}
& V_2=67 \\
& T_1=0^{\circ} \mathrm{C}=273 \mathrm{~K}
\end{aligned}
$$
$$
\begin{aligned}
\therefore \quad T_2=273 \times \frac{67}{47.5} & =385.07 \mathrm{~K} \\
& =112^{\circ} \mathrm{C}
\end{aligned}
$$
Hence, the correct answer is option: 'D'.