Positive deviation from ideal behaviour takes place because of

Options

A. finite size of atoms and `pV//nRT lt 1`
B. molecular interaction between atoms and `pV//nRT gt 1`
C. finite size of atoms and `pV//nRT gt 1`
D. molecular interaction between atoms and `pV//nRT lt 1`

Answer

C

Explanation

According to the van der Waals equation , we have
`(p + (an^(2))/(V^(2))) (V - nb) = nRT`
When molecular interaction (i.e., attraction ) is insignificant , then the `an^(2)//V^(2)` may be neglaected relative to `p` to give
`p(V - nb) = RT`
or `pV - npb = nRT`
or `pV = nRT + npb`
Dividing both sides by `nRT` , we have
`(pV)/(nRT) = 1 + npb`
Thus , `pV//nRT gt 1`
This happens whenn the factor `b` which measures the size of particles is significiant.