Consider compounds A, B and C with following structural formulae
A = $$CH_3 - CH_2 - CH_2 - CH_2 - CH_2 - OH$$
B = $$CH_2 = CH - CH_2 - CH_2 - CH_3$$
C = $$HO - CH_2 - CH_2 - CH(OH) - CH_3$$
For the conversion of B from A, reagent (D) required is _______ and structural formula of product (E) obtained when C undergoes same reaction using excess reagent (D) is _______.

Compound A, $$\mathrm{CH_3CH_2CH_2CH_2CH_2OH}$$, is a primary alcohol. Conversion of A to B, $$\mathrm{CH_2=CHCH_2CH_2CH_3}$$, involves dehydration of the alcohol.

The reagents commonly used for dehydration are concentrated $$\mathrm{H_2SO_4}$$ or $$\mathrm{H_3PO_4}$$ in the presence of heat.

Hence, reagent D is concentrated $$\mathrm{H_2SO_4}$$ or $$\mathrm{H_3PO_4}$$.

Compound C is

$$\mathrm{HOCH_2CH_2CH(OH)CH_3}$$

In the presence of excess dehydrating agent, both hydroxyl groups undergo dehydration.

The first dehydration gives

$$\mathrm{CH_2=CHCH(OH)CH_3}$$

Further dehydration gives

$$\mathrm{CH_2=CHCH=CH_2}$$

The product formed is 1,3-butadiene, a conjugated diene.

Therefore,

$$\mathrm{E=CH_2=CHCH=CH_2}$$

Hence, the correct option is (D).