A hypsometer is used for determining

Analyze the question: A hypsometer is an instrument. We need to identify what it measures from the options.

Explain the concept: The name comes from the Greek hypsos (height). A hypsometer is a vessel in which water is boiled so that a thermometer can be placed in the steam above the boiling water. In physics practicals it is used to determine the steam point (the upper fixed point) of a thermometer, which is the temperature of steam at standard atmospheric pressure (100°C).

Step-by-step reasoning:

1. The upper fixed point of a thermometer is the steam point, found by placing the thermometer in the steam above boiling pure water. This is exactly what a hypsometer does.
2. The ice point (lower fixed point) is found using melting pure ice in a funnel. No hypsometer is needed.
3. Relative humidity is measured with a hygrometer, such as a wet-and-dry bulb hygrometer.
4. Relative density is measured with a density bottle or hydrometer.

Checking each option:

• A. Steam point: correct
• B. Relative humidity: this is a hygrometer
• C. Ice point: this uses melting ice
• D. Relative density: this uses a density bottle or hydrometer

The hypsometer is also used in a related way to find the boiling point of a liquid, which changes with pressure and altitude. That is why it can be used to estimate height.

Answer: A. steam point

Exam tip: Match instruments to their measurements:

• Hypsometer is for the steam point
• Hygrometer is for humidity
• Hydrometer is for liquid density
• Barometer is for pressure

Remember: Hypsometer = Hot steam.