What happens to the speed of particles in a gas as temperature increases?

• A. Speed decreases.
• B. Speed stays the same.
• C. Speed increases.
• D. Speed becomes zero.

Answer: (C)

Speed of gas particles rises with temperature because temperature reflects the average kinetic energy of the particles. In kinetic theory, the average translational kinetic energy is proportional to absolute temperature (in Kelvin). Since kinetic energy is (1/2) m v^2, higher temperature means the typical v^2 increases, so the average speed increases. The Maxwell-Boltzmann distribution shifts toward higher speeds as temperature goes up, with the root-mean-square speed v_rms ∝ sqrt(T). So, as temperature increases, the speeds of particles become larger on average, even though some individual particles may move slower.