Thermometer: Practice Problem & Solution

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Thermometer. Understanding the underlying formula is key to arriving at the correct answer below:

Using the relation $\frac{T - \text{LFP}}{\text{UFP} - \text{LFP}} = \text{constant}$, we write $\frac{T - 0}{100 - 0} = \frac{T - 40}{80 - 40}$. This simplifies to $\frac{T}{100} = \frac{T - 40}{40}$, which gives $40T = 100T - 4000$ or $60T = 4000$, hence $T = \frac{200}{3}\,^\circ\text{C}$.