Question

Absolute zero is defined as the temperature

• A. at which all molecular motion ceases
• B. at which liquid helium boils
• C. at which ether boils
• D. All of the above

Answer 1

The Correct Option is A

The question asks about the definition of absolute zero. Absolute zero is a fundamental concept in chemistry and physics related to temperature.

Explanation:

1. Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance.
2. At absolute zero, theoretically, all molecular motion ceases. This is because temperature is a measure of the average kinetic energy of the particles in a substance.
3. In Kelvin, absolute zero is 0 K, and in Celsius, it is -273.15°C.

Among the options, the correct answer is "at which all molecular motion ceases" because this aligns with the scientific definition of absolute zero.

Let's also consider why other options are incorrect:

• At which liquid helium boils: Helium boils at approximately 4.2 K, which is above absolute zero.
• At which ether boils: Ether boils at a much higher temperature of around 34.6°C, which is completely unrelated to absolute zero.
• All of the above: This cannot be the correct answer as only one statement matches the definition of absolute zero.

Conclusion: Thus, the correct option is "at which all molecular motion ceases" because absolute zero is theoretically the point where all molecular or atomic motion stops, which helps in understanding the fundamental limits of the temperature scale.