The table shows the amount of radioactive element remaining in a sample over a period of time. Radioactive Decay Rate

Amount of Radioactive Sample

(grams) Time(years)

56.0 - 0

47.1 - 400

39.6 - 800

33.3 - 1,200

28 - 1,600

Part 1: What is the half-life of the element? Explain how you determined this.

Part 2: How long would it take 312 g of the sample to decay to 9.75 grams? Show your work or explain your answer.

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.

particle   p is an electron and particle q is a neutron