Which of the following reagents is used to convert a $C \equiv C$ triple bond to a $C=C$ double bond to give the $Cis$ isomer of an alkene?

Identify the correct order of acidic strength for the following hydrocarbons:

For the alkyne with formula $C_6H_{10}$,the number of alkynes with acidic hydrogens is $x$ and the number of alkynes with no acidic hydrogens is $y$. $x$ and $y$ are respectively:

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 Lindlar's catalyst? Write its uses.

Give a brief note on the acidic nature of alkynes.