Derrick just got home from playing soccer on a muddy field. he is curious how different brands of laundry detergent compare in removing mud from clothes, so he sets up an experiment. in one laundry load, he puts his muddy socks with brand a detergent. in the next load, he puts his muddy jersey with brand b detergent. in the final load, he puts his muddy shorts with brand c detergent. afterward, he noticed that the jersey came out the cleanest. he concludes that brand b is the best detergent for removing mud from clothes. is his conclusion valid? a. no; derrick was biased toward brand b. b. no; there were too many variables in the experiment. c. no; there were too many controls in the experiment. d. yes; the experiment was set up correctly.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

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.