What is obtained when chloroform is heated with $Ag$ powder?

If acetylene is passed through an electric arc in the atmosphere of nitrogen,the compound formed is

Predict the product of the following reaction sequence:
$HC \equiv CH$ $\xrightarrow[\begin{smallmatrix} (2) \text{ excess } I-CH_2-(CH_2)_2-CH_3 \\ (3) \text{ } H^{\oplus} \end{smallmatrix}]{(1) \text{ excess } NaNH_2}$

In the reaction,$H_3C-C\equiv C-H$ $\xrightarrow[2. x]{1. NaNH_2, \Delta}$ $\xrightarrow{3. y} H_3C-CH=CH-CH_3$ (trans form),$x$ and $y$,respectively are

What is the product obtained upon hydrogenation of the following compound in the presence of a poisoned palladium catalyst?

The general formula of an alkyne is: