Question

A unknown gas 'A' decolourises bromine in $CC{l}_4$ and forms a precipitate with ammoniacal silver nitrate. The gas 'A' is:

• A. $C_2{H}_2$
• B. $C_2{H}_4$
• C. $C_2{H}_6$
• D. $C{H}_4$

Answer 1

The correct option is A $C_2{H}_2$

Acetylene gas decolourises bromine in $CC{l}_4$$CH\equiv CH+2B{r}_2\stackrel{CC{l}_4}{⟶}B{r}_{2}CH-CHB{r}_2$
Acetylene reacts with ammoniacal silver nitrate to produce disilver acetylide.
$CH\equiv CH\to +2\left[Ag\right(N{H}_3{)}_2]N{O}_3\to \stackrel{+}{A}g\stackrel{-}{C}\equiv C^{-}A{g}^{+}\downarrow ppt$