Question

What is the reference point of thermometer in celsius scale

Answer 1

The most likely answer is the boiling point and freezing point of water. The Celsius scale starts at the freezing point of water (0°C) and than scaled so that 100°C fell on the boiling point of water.

Answer 2

The thermometers with Celsius scale are calibrated form 0° to 100° where there two temperatures are the freezing and boiling of water.