Question

water is no suitable for barometer.why?

Answer 1

Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference.

Answer 2

Well you could use water in a barometer - but there are two main reasons why mercury is better....☺

First = Mercury is much more dense (about 13 times) than water, so a barometer of water would have to be much larger than a mercury one....☺

Second = mercury hardly evaporates at all, while water evaporates very readily - so a mercury barometer is much more stable and long-lasting than a water one......☺