The ratio of carbon-14 to carbon-12 in a piece of charcoal from a fire pit in an archaeological excavation is found to be 12.5% of that in a sample of modern wood. Approximately how old is the site? (Carbon-14 half-life is 5730 years.) Answer as a whole number with no units.

17190 years          

Explanation:

The exponential decay equation is:

Where:

N(t) is the quantity at time t

N₀ is the initial amount

λ is the decay constant = ln(2)/t(1/2)

t(1/2) is the half-life    

Since the ratio of carbon-14 to carbon-12 is 12.5%, we have that:

By solving the above equation for t:

Therefore, the site is 17190 years old.  

I hope it helps you!

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.