$CaC_2 + 2D_2O \longrightarrow$ "$P$" $+ Ca(OD)_2$
In the above reaction,the product "$P$" is:

$1$-butyne can be distinguished from $2$-butyne by

What is the major organic product of the following reaction?
$Ph-C \equiv CH \xrightarrow[H_2SO_4]{Hg^{2+}, H_2O} ?$

Which of the following is suitable for the preparation of alkene from alkyne?

Consider the following reaction sequences and choose the correct option:
$L \xrightarrow{Na/liq. NH_3} Ph-C \equiv C-Me \xrightarrow[Lindlar's \ Catalyst]{H_2, Pd/C} K$
$L \xrightarrow{HBr, \text{benzoyl peroxide}} N$
$K \xrightarrow{HBr} M$

The synthesis of $3$-octyne is achieved by adding a mixture of sodium amide and an alkyne to a bromoalkane. What are these bromoalkane and alkyne?