Why mercury is preferred as thermometric liquid in making thermometers?why is alcohol preferred as thermometric liquid in making thermometers?

What happens to radiant heat when it falls on body?

Both, alcohol and mercury preferred as thermometric liquids in making thermometers.

Mercury preferred to other liquids because:

1.   Mercury is the only metal which is found in liquid state. Mercury is a good conductor of heat.
2.   Mercury is opaque and has a shining silvery color white liquid which can be clearly visible in the capillary tube of a thermometer.
3.   Mercury doesn't stick to the wall of the thermometer.
4.   Mercury has a high boiling point of about 357oC and therefore can be used to measure temperatures as high as 357oC.   Mercury has a freezing point of about −39oC and is suitable to record low temperatures.
5.   Mercury thermometer used in tropical climates.

Alcohol preferred to other liquids because:

For measuring very low temperature alcohol thermometer is suitable due to alcohol freezes at -117oC. Alcohol thermometer is used in cold climate. 

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mercury is considered as a thermometric liquid because mercury's melting point is in around 318 deg celcius, while water's melting point is 100 deg celcius.it is also because most metals conducts heat in room temperature in solid form while mercury conducts in liquid form.alchohol is now preffered because mercury is toxic when it is out of the thermometer.so mercury is now banned in all countries.

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