Question

The gaseous substance which decolourises bromine but does not give a precipitate with ammoniacal silver nitrate is:

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

Answer 1

The correct option is B $C_2{H}_4$

decolourisation of bromine water is the test of an alkene.
ammoniacal silver nitrate is used to test the presence of carbonyl compound i.e. aldehyde or ketone.
Thus only $C_2{H}_4$ will gove bromine water test but not silver mirror test.