An ideal thermometer should have

Before use, the mercury level in clinical thermometer should be below __________.

Clinical thermometer should not be immersed in ________ water.

Why a clinical thermometer should not be sterilized by boiling water?

The resistance of an ideal voltmeter should be :

Boojho has three thermometers as shown in figure. He wants to measure the temperature of his body and that of boiling water. Which thermometer (s) should he choose?