The correct answer is Used to measure atmospheric pressure. CONCEPT: Barometer:
●A barometer is a scientific instrument that is used to measure air pressure. ● The height of the level of mercury in the tube is nearly76 cm above the free level of mercury in the trough. ● Formula to calculate the atmospheric pressure is, Pa=ρgh ● The reading in the barometer can be calculated by the formula h=
pa
pg
Where, ρ = density of mercury, g = acceleration due to gravity, and h = vertical distance. EXPLANATION: ● From above it is clear that the mercury column in the barometer is used to measure atmospheric temperature Extra point: This are some of the device and their application