Given below are two statements : Statement I : Gallium is used in the manufacturing of thermometers. Statement II : A thermometer containing gallium is useful for measuring the freezing point (256 ~K) of brine solution. In the light of the above statements, choose the correct answer from the options given below :

Statement I is true but Statement II is false

Both Statement I and Statement II are true

Statement I is false but Statement II is true

Both Statement I and Statement II are false

P Block Elements PYQ — JEE Main 2024 · 6 Apr · Shift 1 · Q9 with Solution

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Correct answer: B

Analyze Statement I: Gallium is used in the manufacturing of thermometers.
- Gallium has a very low melting point: $T_m \approx 29.8^\circ\text{C} = 302.9\,\text{K}$
- Because of its liquid range and low toxicity compared to mercury, gallium (or gallium-containing alloys) can be used in certain thermometers.
Hence, Statement I is true.
Analyze Statement II: A thermometer containing gallium is useful for measuring the freezing point $(256\,\text{K})$ of brine solution.
- The freezing point given is: $256\,\text{K} = 256 - 273 = -17^\circ\text{C} \text{(approximately)}$
- But pure gallium solidifies at about: $302.9\,\text{K} \approx 29.8^\circ\text{C}$
- Since $256\,\text{K}$ is far below gallium’s melting point, gallium would already be solid, so such a thermometer would not function for measuring that temperature.
Hence, Statement II is false.
Choose the correct option:
- Statement I: True
- Statement II: False
Therefore, the correct option is: $\boxed{\text{B}}$