What temperature does a thermometer need to be calibrated at boiling point?

The boiling point of water at standard atmospheric pressure is typically considered to be 212°F (100°C). When calibrating a thermometer, it is essential to ensure that it accurately reflects this standard boiling point. The practice usually involves placing a thermometer in boiling water and verifying that it reads 212°F.

If a thermometer is being calibrated at boiling point, the reading should read as closely as possible to this established temperature (212°F) to ensure its accuracy. Therefore, calibrating it at temperatures significantly lower, such as 210°F, 220°F, or 200°F, does not align with standard calibration procedures, as these temperatures do not represent the accurate boiling point of water.

Thus, the correct answer focuses on the significance of the boiling point being the standard against which thermometers are calibrated, making 212°F the appropriate calibration point. It's essential to follow these standards to ensure the accuracy of measurements in health departments and related fields.