Q. The most readily dehydrated compound among the following is

 1920  183 Aldehydes Ketones and Carboxylic Acids Report Error

Solution:

The ease of dehydration of the given compounds can be explained on the basis of the stability of the carbocation formed. In case of options (a), (b) and (d), a secondary carbocation is formed but the presence of an electron withdrawing group adjacent to the positively charged carbon, intensifies the charge and hence destabilises the species.
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However, in case of option (c), a secondary carbocation is formed, but the electron withdrawing group is present farther away, as a result, the effect of this group is diminished and hence the carbocation is relatively more stable.
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