Mercury boils at 367°C. However, mercury thermometers are made such that they can measure temperature up to 500°C. This is done by [CPMT 2004]

Filling nitrogen gas at low pressure above the mercury level

Maintaining vacuum above mercury column in the stem of the thermometer

Filling nitrogen gas at high pressure above the mercury column

Filling nitrogen gas at low pressure above the mercury level

Filling oxygen gas at high pressure above the mercury column

Mercury boils at 367°C. However, mercury thermometers are made such t

1.	Mercury boils at 367°C. However, mercury thermometers are made such that they can measure temperature up to 500°C. This is done by [CPMT 2004]
A.	Maintaining vacuum above mercury column in the stem of the thermometer
B.	Filling nitrogen gas at high pressure above the mercury column
C.	Filling nitrogen gas at low pressure above the mercury level
D.	Filling oxygen gas at high pressure above the mercury column
Answer» C. Filling nitrogen gas at low pressure above the mercury level