The product $(C)$ of the reaction is:

Arrange benzene,$n$-hexane and ethyne in decreasing order of their acidic behaviour.

Write the main product of the given reactions:
$(1)$ $C_6H_5CH = CH_2 \xrightarrow{HBr}$
$(2)$ $C_4H_{10} \xrightarrow{\text{air}, \Delta}$

The major product $[C]$ of the following reaction sequence will be

What are $X$ and $Y$ respectively in the following sets of reactions?
$I. \ CH_3CH_2CH_2OH \xrightarrow{PBr_3} X$
$II. \ CH_3CH=CH_2 \xrightarrow{HBr, (C_6H_5COO)_2} Y \text{ (major)}$

Which of the following reactions do not represent the major product of given Birch reductions?