Concept:Polarizability is a measure of how easily the electron cloud of an atom or molecule can be distorted to induce a temporary dipole. It strictly depends on the size and volume of the electron cloud.
Formula:$$ \alpha \propto \text{Molecular Size / Number of Electrons} $$
Solution:- All the options are aliphatic hydrocarbons governed entirely by London dispersion forces.
- To determine polarizability, we simply evaluate the size of the molecules. A longer carbon chain has more electrons spread over a much larger volume.
- Option D is Ethane (2 carbons), B is Propene (3 carbons), C is Pentane (5 carbons), and A is Hexane (6 carbons).
- Hexane (\( \text{C}_6\text{H}_{14} \)) is the largest molecule in the list. Its massive, extended electron cloud is the least tightly controlled by the nuclei, making it the easiest to dynamically distort. Thus, it exhibits the maximum polarizability.
Why other options are incorrect:The other molecules have shorter carbon chains, fewer electrons, and smaller, tighter electron clouds, resulting in lower polarizability and lower boiling points.
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