`[A] underset(250^(@)C)overset(Al_(2)O_(3))(rarr) [B] underset((ii) AgOH)overset((i) HI)(rarr) [C] underset(250^(@)C)overset(Al_(2)O_(3))(rarr) [B] underset((ii) H_(2)O_(2)//OH^(-))overset((i) B_(2)H_(6))(rarr) [A]`
In the above reaction scheme [A] and [C] are isomers. [B] has a formula `C_(5)H_(10)` which can also be obtained from the product of the reaction of `CH_(3)CH_(2)MgBr` and `(CH_(3))_(2)CO`. Give the structures of [A], [B] and [C].

Explanation

(i) The compound [B] with the formula `C_(5)H_(10)` can be prepared from `CH_(3)CH_(2)MgBr` and `(CH_(3))_(2)CO` as follows :
`underset("Propanone Ethyl mag. bromide")(CH_(3)-underset(CH_(3))underset(|)overset(O)overset(||)(C)+CH_(3)CH_(2)MgBr) rarr underset("Addition compound")([CH_(3)-underset(CH_(3))underset(|)overset(OMgBr)overset(|)(C)-CH_(2)CH_(3)])overset(H_(2)O //H^(+))(rarr)underset([C])(CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)(C)-CH_(2)-CH_(3)) underset("2-Methylbut-2-ene [B]")(overset(-H_(2)O)(rarr)CH_(3)-underset([C_(5)H_(10)])underset(CH_(3))underset(|)(C)=CH-CH_(3))`
(ii) Since [B] has been formed by the dehydration of [C] with `Al_(2)O_(3)`, the compound [C] is a tertiary alcohol and is isomeric with secondary alcohol [A]. Both [A] and [C] cab be represented as :
`underset([C])underset("2-Methylbutan-2-ol")(CH_(3)-underset(CH_(3))underset(|)overset(OH)overset(|)(C)-CH_(2)-CH_(3))" "underset([A])underset("3-Methylbutan-2-ol")(CH_(3)-underset(CH_(3))underset(|)(CH)-underset(OH)underset(|)(CH)-CH_(3))`
(iii) Starting from [A], the sequence of reactions may be shown as follows :