Complete the lewis structures of the atoms and ions by adding electrons, as needed.

a) li

b) na

c) na+

d) f-

Lewis structure are defined structure which represents the number of valence electrons present around the atom in a molecule. They are known as Lewis electron dot structures.

Valence electrons are the electrons present in the valence shell of an atom.

A) Lithium has total three electrons out of which one is valence electron as we see that from its electronic configuration.

[Li]=, For Lewis structure see figure (I)

B) Sodium has total 11 electrons out of which one is valence electron as we can see that from its electronic configuration.

[Na]= For Lewis structure see figure (II)

C) In sodium cation, there are total 10 electrons, since it will easily loose its one valence electron to attain noble gas configuration by which there will be no valence electron present in it. So, its electronic configuration becomes

For Lewis structure see figure (III)

D) In fluorine anion, there are total 10 electrons out of which 9 electrons are of its own and one electron is being added in its valence shell ,so that it can attain noble gas configuration.

 For Lewis structure see figure (IV)

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.

i'm pretty sure its b i might be wrong though!