List four parameters of comparison between mercury and water as barometric liquid.

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Solution

Following are the four parameters of comparison between mercury and water as barometric liquid.
Mercury as barometric liquid Water as barometric liquid
Length of glass tube: The glass tube doesn't need to be longer.
Explanation:
Mercury being the heaviest liquid rises to 76 cm to balance the atmospheric pressure. Therefore, the glass tube can be kept short.
The glass tube needs to be longer.
Explanation:
Water, being 13.6 times lighter than mercury, will rise to 13.6 times larger than mercury. Hence, the glass tube needs to be much longer.

Mercury is a metal and a good conductor of heat and has comparatively lower specific heat and can come to the same temperature of the atmosphere more quickly. Water on the other hand is having higher specific heat and takes comparatively more time to come to the same temperature of the atmosphere.
Mercury, being metal has a shining quality and the reading is highlighted clearly. Water, being dull in appearance the reading is not highlighted clearly.
Mercury doesn't stick to the glass hence there is very little chance of a stray drop of mercury obscuring the reading. Water sticks to the glass so we would need a tube of greater diameter.

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