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

Which of the following reagents is used to distinguish propene and propyne?

Acetylene shows ........... in its reaction with silver nitrate.

An inorganic metal oxide $(A)$ heated with carbon gives compound $(B)$,which on reaction with water gives ethyne. What are the compounds $(A)$ and $(B)$?

The reaction of acetylene with acetic acid in the presence of $Hg^{2+}$ at room temperature yields ....

The compound belonging to the homologous series of ethyne is .........