Final answer:
The statement is true; evaporation from a wet-bulb thermometer's wick depends on the moisture content, or relative humidity, of the surrounding air, with high humidity slowing evaporation and low humidity accelerating it.
Step-by-step explanation:
True, the rate at which water will evaporate from the wick on the wet-bulb thermometer is determined by the moisture content of the surrounding air. When air has a high moisture content, or relative humidity, it can hold less additional water vapor, which results in a lower rate of evaporation from the wet bulb.
Conversely, air with low moisture content has a higher capacity for water vapor, leading to a faster evaporation rate from the wet bulb.
The actual evaporation rate is inversely related to the relative humidity; as relative humidity approaches 100%, evaporation is inhibited because the partial pressure of water vapor in the air is close to the vapor pressure of water.
The wet-bulb thermometer is used to measure the relative humidity of the air. When the surrounding air has low moisture content, the rate of evaporation from the wick is higher because there is a greater difference in water vapor pressure between the wick and the air. This causes the water to evaporate more quickly.