Answer
To double the root-mean-square average speed, the absolute temperature T must quadruple, i.e., increase by a factor of 4.
Work Step by Step
Equation 18.19 relates the root-mean-square average speed of atoms to the absolute temperature.
$$v_{rms}=\sqrt{\frac{3kT}{m}}$$
To double the root-mean-square average speed, the absolute temperature T must quadruple, i.e., increase by a factor of 4.