1.Give the main feature of solid, liquid and gas?

 (i)Solid gas a definite shape and occupies only a definite volume
 (ii)Liquid does not have a definite shape . It takes the shape of the container
 (iii)Gas does not have a definite shape . It also takes the shape of the container

2.Explain how temperature of a gas can be measured?

The temperature of  a gas is generally measured by a thermometer . When the thermometer is placed in contact with the gas , the level of mercury gives the temperature . It is expressed either in 0C or oK.
3.Mansion some of certain special properties of gas?

  (i)Gas is composed of very small particles called molecules
 (ii)The force of attraction between the molecules of gas is negligible
 (iii)Molecules of a gas move in different direction
  (iv)Gases are light and posses very light weight
4.Give a short about the movement of molecules of a gas?

Molecules of a gas move in different directions. The gas molecules move in straight lines . Gas molecules undergo random collision with other molecules and occupy the volume that is available.
5.When a person travels against wind an a bicycle he has to peddle laid to move .Why?

The person travelling against the wind an a bicycle has to peddle hard to move because the gas exerts pressure . If he travels in the direction of the wind flow he moves forward without much effort.
6.What is a Barometer?

Barometer is a device used to measure the pressure exerted by a gas . It can be devised very easily. Here pressure is measured and represented in terms of atmospheres.
7.Explain the constriction of a mercury barometer.
 
Take a long glass tube of 100 can closed at one end and with a narrow bore. Fill it up completely with mercury . Invert it gently into a reservoir filled with mercury. When it is inverted an empty space is aerated in the tube . The length of the mercury column starting from the reservoir level is equal to pressure exerted by air.
8.What is a manometer?

All the gases existing in the nature exert pressure . Pressure exerted by any gas can be measured with the help of a modified barometer which is known as a manometer.
9.Explain the pressure measured using a manometer?

Here gas is present in the cylinder which is with a stop cock and attached to a ‘ v ‘ tube having mercury in it. To know the pressure exerted by the gas, measure the mercury level in the longer limb of the glass tube ( l1 ) . Connect the V – tube to gas cylinder. The mercury level rises to ( l 2 ) due to pressure of the gas . Then the pressure exerted by the gas = l2 – l1 .
10.What is compressibility?
The volume of a given mass of gas can be easily compressed. Decrease in the volume of the some quantity of gas under pressure is known as compressibility. As the pressure on a gas increases, compressibility also increases.
11.What is the Boyle’s law?

It explains the effect of pressure on volume of gas . Boyles law states that the volume of a given mass of gas is inversely proportional to its pressure at any given temperature . It can be mathematically given as;

Where V is volume , P is pressure of gas at temperature T.
12.Explain the significance of Boyles law?

  According to Boyles law,

i.e v = ( k )

Where k is the proportionality constant.

Thus we get; P V = K = constant

Thus according to Boyles law , at constant temperature ( T ) , volume of a given mass of gas ( v ) decrease with an increase in pressure ( p )

13. A gas of given mass is allowed to expond from a volume of 500 ml 100 ml. What is the pressure of gas before expansion if the pressure after expansion is 5 atm

Initial volume (v₁) = 500 ml

Final volume ( V₂) = 1000 ml

Inital pressure = P₁

Final pressure ( P₂ ) = 5 atm

According to Boyles law

P₁ v₁ = p₂V₂

P1 = 

                         P1 = 10 atm