What is the volume (in liters) of a 4.00 m solution needed to make 250 ml of a 0.400 m solution?

Molarity is the concentration of a solution expressed as the number of moles of solute per litre of solution.

To get the molarity, you divide the moles of solute by the litres of solution.

Molarity=moles of solutelitres of solution

For example, a 0.25 mol/L NaOH solution contains 0.25 mol of sodium hydroxide in every litre of solution.

To calculate the molarity of a solution, you need to know the number of moles of solute and the total volume of the solution.

To calculate molarity:

pure substance: iron,copper

impure substance: water,charcoal

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.