$2$-Hexyne reacts with $.......$ to give $trans-2$-hexene.

$A$ compound $C_5H_8$ gives a white precipitate with ammoniacal $AgNO_3$. It yields $(CH_3)_2CHCOOH$ upon oxidation with hot alkaline $KMnO_4$. The compound is:

When acetylene reacts with $HCl$ in the presence of $HgCl_2$,the product formed is.........

Which reagent is used for the following transformation? $Br-CH_2-CH_2-Br \rightarrow H-C \equiv C-H$

An acyclic hydrocarbon $P$ with molecular formula $C_6H_{10}$ produces acetone as the only organic product through the following reaction sequence,where $Q$ is an intermediate organic compound:
$P (C_6H_{10})$ $\xrightarrow[(ii) NaBH_4/ethanol, (iii) dil. acid]{(i) dil. H_2SO_4/HgSO_4} Q$ $\xrightarrow[(ii) O_3, (iii) Zn/H_2O]{(i) conc. H_2SO_4 (catalytic amount), (-H_2O)} 2 CH_3COCH_3$
$1.$ The structure of compound $P$ is:
$(A)$ $CH_3CH_2CH_2CH_2-C \equiv C-H$
$(B)$ $H_3CH_2C-C \equiv C-CH_2CH_3$
$(C)$ $(CH_3)_2CH-C \equiv C-CH_3$
$(D)$ $(CH_3)_2CH-C \equiv C-H$
$2.$ The structure of compound $Q$ is:
$(A)$ $(CH_3)_2CH-CH(OH)-CH_2CH_3$
$(B)$ $(CH_3)_2CH-CH(OH)-CH_3$
$(C)$ $(CH_3)_2CH-CH_2CH(OH)CH_3$
$(D)$ $CH_3CH_2CH_2CH(OH)CH_2CH_3$
Identify the correct options for $1$ and $2$.

What is the end product of the following sequence of operations?
$CaC_2$ $\xrightarrow{H_2O} A$ $\xrightarrow[Hg^{2+}]{dil. H_2SO_4} B$ $\xrightarrow[H_2]{Ni} C$