The right answer is B: water at 99°C. The speed of molecular motion, or the kinetic energy of water molecules, is directly related to the temperature of the water. The higher the temperature, the faster the molecular motion. Therefore, among the given options, water at 99°C (Option B) has molecules vibrating at the fastest speed.
Temperature is a measure of the average kinetic energy of the molecules in a substance. As temperature increases, the kinetic energy of the molecules also increases, leading to higher molecular motion. In this case, water at 99°C is at a higher temperature compared to the other options, indicating that its molecules have higher kinetic energy and are vibrating at a faster speed.
Options A, C, and D represent water samples at different temperatures, but water at 99°C (Option B) has the highest temperature, making it the sample where the molecules are vibrating at the fastest speed.
Therefore, the correct option is B: water at 99°C.
The question probable may be:
You have four water samples at different temperatures. In which sample are the molecules vibrating at the fastest speed?
A. water at 37°C
B. water at 99°C
C. water at 99°F
D. water at 299K