Discussion
The correct gas phase acidity order for alcohols FCH2OH, CH3OH, ClCH2OH and BrCH2OH is
Answer: D
The key gives \(\mathrm{ClCH_{2}OH > BrCH_{2}OH > FCH_{2}OH > CH_{3}OH}\).
Acidity depends on how well the alkoxide ion XCH2O- is stabilised. A halogen on the carbon next to oxygen withdraws electron density inductively and spreads the negative charge, so every halomethanol is more acidic than methanol. That places CH3OH last and rules out the two options that put it, or FCH2OH below it, anywhere else.
Among the halogens, the gas phase removes solvation, and the ranking is no longer set by electronegativity alone: the polarisability of the halogen also helps disperse the charge. The key's order reflects chlorine combining a strong inductive pull with greater polarisability than fluorine, ahead of bromine, with fluorine last of the three. The option headed by FCH2OH is the inductive-effect-only reading that the key does not follow.
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