In caves, dripping groundwater containing calcium bicarbonate can form stalactites and stalagmites. when the water is exposed to air, some of the calcium bicarbonate turns into calcium carbonate, which gets deposited on the ground. what makes this process a chemical change?
a. a new substance is formed in this process, which is an important clue to chemical change.
b. a change in state is observed in this process, which is an important clue to chemical change.
c. this process involves separation of dissolved substances, which is an an important clue to chemical change.
d. this process involves dissolving substances together, which is an an important clue to chemical change.
e. this process involves breaking and reshaping of substances, which is an an important clue to chemical change.

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

thats a little if u want the answer just look it up on google thats what i do haha : )