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 :

Solution

Chemistry ma’am · 4 steps

Gallium is liquid only above 303 K, so it reads hot things, not a freezing brine at 256 K.

1. Gallium's liquid range. Gallium melts at about 303 K and boils at about 2676 K. No other common metal stays liquid over such a wide range of temperature.
2. Statement I. A thermometer needs a liquid that expands smoothly and does not boil away. Because gallium stays liquid up to about 2676 K, it is used in high-temperature thermometers. Statement I is true.
3. Statement II. Brine freezes at 256 K, which is about 47 K below gallium's melting point. At that temperature the gallium itself is a solid, so it cannot rise or fall in the tube. Statement II is false.
4. So. Statement I is true and Statement II is false, which is option (b).

The idea to keep. A thermometer liquid works only between its own melting and boiling points. Gallium covers about 303 K to 2676 K, so it is good for high temperatures and useless below room temperature.

Answer from the NTA final answer key. Solution by PrepWiser.