#### For real gases van der Waals equation is written as Where 'a' and 'b' are van der Waals constants.Two sets of gases are:(I)    O2, CO2, H2 and He(II)    CH4, O2 and H2The gases given in set - I in increasing order of 'b' and gases given in set - II in decreasing order of 'a' are arranged below. Select the correct order from the following: Option 1) (I) O2<He<H2<CO2 (II) H2>O2>CH4 Option 2) (I) H2<He<O2<CO2 (II) CH4>O2>H2 Option 3) (I) H2<O2<He<CO2 (II) O2>CH4>H2 Option 4) (I) He<H2<CO2<O2 (II) CH4>H2>O2

As we learnt in

Vander waal constants -

Vander waal constant ‘a’ is measure of intermolecular attraction of a gas

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Vander waal Constant -

Vander Waal constant ‘b’ is measure of size of molecule

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Van der Waals constants a & b

a is the measure of intermolecular attraction of gas , b is the measure of the size of the molecule. So, the increasing order of b is clearly.

and the decreasing order of a is

Option 1)

(I) O2<He<H2<CO2 (II) H2>O2>CH4

Incorrect

Option 2)

(I) H2<He<O2<CO2 (II) CH4>O2>H2

Correct

Option 3)

(I) H2<O2<He<CO2 (II) O2>CH4>H2

Incorrect

Option 4)

(I) He<H2<CO2<O2 (II) CH4>H2>O2

Incorrect