In an undisturbed stack of rock layers, each containing fossils of once-living organisms, where would some evidence of the most ancient life forms most likely be found?

In the bottom layer.

Explanation:

The rule of the fossil formation is that the first layer that is formed is at the bottom of the stack. The second layer contains less organism than the first layer.

This is the principle of super position that the first layer formed will be at the bottom and the newest layer formed will be at the top of the soil in the stacking.

Hence, most of the fossils will be found in the oldest layer of the soil which means at the bottom of the soil.

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.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.