Question

Absolute zero temperature is the temperature at which:

• A. mass becomes zero
• B. volume becomes zero
• C. all molecular motion ceases
• D. the temperature of substance is zero

Answer 1

Answer: (B)

Absolute zero (-273K) is the temperature at which all gases are supposed to occupy zero volume. According to Charle's law $V_t=V_0\left(1+\frac{t}{273}\right)$ $V_{-273}=V_0\left(1-\frac{273}{273}\right)$ $V_{-273}=0$ This means that further lowering of temperature is impossible because it would correspond to negative volume which is meaningless. Thus the lowest temperature which can be obtained is -273 K which is very difficult to obtain as it is impossible to reduce volume to zero. At absolute zero the molecules of gas has zero kinetic energy i.e., any type of molecular motion ceases.