1. I am in the same family as lead, and I have fewer protons than Na. Who am I? 2. I have more protons than chlorine but less than potassium. Who am I?
3. My atomic number is below sodium, and I am a metal in the same family as sodium. Who am I?
4. I have more valence electrons than S and one less proton than Ar. Who am I?
5. My atomic number is one above Au. Who am I?
6. I have half as many protons as zinc. Who am I?
7. If I had one more proton, electron, and neutron, I would be Zn. Who am I?
8. I am in Group 1. I have a higher atomic number than Ar, but a lower atomic number than Br. Who am I?
9. I have the most protons of any element in Group 4. Who am I?
10.I am in the same group as magnesium, and I have fewer electrons than any element in my group. Who am I?

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.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.