Pyroheliometer : Radiation
Calorimeter : Heat
Planimeter : Area
Barometer : Humidity
Answer is Right!
Answer is Wrong!
The correct answer is D. Barometer : Humidity.
A pyroheliometer is an instrument used to measure solar radiation. A calorimeter is an instrument used to measure heat. A planimeter is an instrument used to measure area. A barometer is an instrument used to measure air pressure.
Humidity is the amount of water vapor in the air. It is not measured by a barometer.
The other three pairs are all related in that the first word is an instrument that measures the second word.