What is the primary function of a manometer in a laboratory setting?

In a U-tube manometer, if the height difference is 0.5 meters and the liquid density is 1000 kg/m³, what is the pressure difference being measured? (Assume g = 9.81 m/s²)

In a manometer experiment with an unknown gas, the liquid is oil with a density of 900 kg/m³. If the height difference is 0.25 meters, what is the unknown gas pressure given atmospheric pressure is 100,000 Pa? (Use g = 9.81 m/s²)

Convert a pressure reading of 2 atmospheres into pascals.

If the top pressure in a manometer is 100 kPa and the liquid density is 850 kg/m³ with a height difference of 0.6 meters, what is the bottom pressure? (Use g = 9.81 m/s²)