When sodium reacts with chlorine, sodium chloride is produced. andrew represented this reaction with this equation: na + cl2 → 2nacl

The correct representation of reaction will be:

Explanation:

Reaction represented by Andrew is not correct as it is not a chemical reaction balanced. Whenever a chemical reaction takes place mass of the reactants always remains conserved as a per as law of conservation of mass.

The law states that mass can neither be created nor be destroyed. And in a balanced chemical reaction number total mass of reactants is always equal to the total mass of products.

The correct representation of reaction will be:

Number of sodium atoms and chlorine atoms on the both sides are equal

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.