The increasing order of reactivity of the following compounds towards acid catalyzed dehydration is
(a) CH₃-CH₂-OH

(d) CH₃-C(CH₃)₂-OH
Choose the correct answer from the options given below.

Order of reactivity of alcohols towards acid catalyst dehydration is 3° > 2° > 1°

$\therefore$a < c < d but option (2) is least because OH group is attached to sp2 hybridised carbon atom and partial bond character develops between C–OH bond.
(1) rate of acid catalysed dehydration reaction $\mathrm{\infty }$ stability of carbocation intermediate formed.

$\text{ (a) }{\mathrm{CH}}_3{\mathrm{CH}}_2-\mathrm{OH}\underset{-{\mathrm{H}}_2\mathrm{O}}{\stackrel{+}{\mathrm{C}}}{\mathrm{H}}_3\stackrel{+}{\mathrm{C}}{\mathrm{H}}_2\text{ (I) }$

Stability order:
II < I < III < IV
Rate of dehydration reaction:
b < a < c < d