Hi, in some texts number of water molecules released during polymerization is 2n but in others 2n-1 , why?

Explanation:

Because you only have one repeat unit, n=1. 2n-1 becomes 2(1)-1 which is equal to one, meaning one molecule of H2O is produced, as is shown by the top condensation polymerisation reaction.

If you had two repeat units, n=2 so 2n-1=3. Three H2O molecules are produced because you would need two molecules of each reactant so three condesation reactions would occur and three molecules of H2O would be released.

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.

m=9

step-by-step explanation: