Hydroboration-oxidation of but$-1-$ene forms

$2,3$-dimethylbut-$2$-ene when reacted with bromine forms a compound which upon heating with alcoholic $KOH$ produces the following major product.

An alkene $'A'$ on ozonolysis gives a mixture of ethanal and pentan$-3-$one. Write the structure and $IUPAC$ name of $'A'$.

Ethyl phenyl acetylene ($1$-phenyl-but-$1$-yne) on reduction with partially deactivated palladised charcoal (Lindlar's catalyst) gives:

$CH_2=CH-CH_2-CH_3 \xrightarrow{H^{+}/\Delta} \text{Major product}$. Identify the major product in the above reaction.

The reaction conditions used for converting $1, 2-$dibromoethane to ethene are