Answer: No one. All these molecules are nonpolar.
Explanation: Dipole-dipole attractions occur only between polar molecules. To know if a molecule is polar, you have to observe if their dipole moment (μ) is different from 0. You can do this by observing the vectors of charge in each molecule.
In all the molecules of the alternatives, the overall molecule is nonpolar (the sum of the vectors is equal to 0). So, these molecules are attracted only by induced dipole forces (weak forces that exist between nonpolar molecules).
For F2, this molecule is nonpolar because is composed of equal atoms. So, there isn't an atom which pulls the charge for itself.
The relative volumes of chloroform and water that should be used is 9:10
Concentration of solution in chloroform =
( moles of chloroform )
Concentration of solution in water =
( moles of water )
Dissociation constant at
; 
Concentration of solution in chloroform / Concentration of solution in water
Meaning;

Since
mole is present in chloroform and
mole is present in water, Total mole of Caffeine present is 
Now, we substitute our given values into the equation

Therefore, the relative volumes of chloroform and water that should be used is 9:10
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Answer: B). little wind
Explanation: Deserts have few large animals, fertile soil, and little rainfall but they have lots of wind