JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Chemical Bonding and Molecular Structure

The interaction energy of London forces between two particles is proportional to

r^{x}

, where

r

is the distance between the particles. The value of

x

is:

(A)-3
(B)-6✓ Correct
(C)6
(D)3

Answer: (B)

Solution

London dispersion arises when an instantaneous dipole in one particle induces a dipole in the other. The field of the instantaneous dipole falls off as

r^{- 3}

, the dipole it induces is proportional to that field, and the interaction energy of the two dipoles carries a further factor of

r^{- 3}

, so the interaction energy varies as

r^{- 6}

. The value of

x

- 6

JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Single correct option

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