Which of the following should be used to measure the temperature of a liquid

The answer is thermometer. Do you have any answer choices?

I don't know the options, but a thermometer should work.

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a