Question

Yellow-coloured flakes when treated with HCl yield gas with a rotten egg odour. Choose the correct statement(s) regarding this chemical reaction. ​

• A. Yellow coloured flake is $N{a}_{2}S$
• B. Gas evolved is $C{O}_2$
• C. Gas evolved is $H_{2}S$
• D. Yellow coloured flake is $CaC{O}_3$

Answer 1

Answer: (A), (C)

Gas evolved is $H_{2}S$

• It’s given that yellow coloured flakes are treated with HCl and it gives rotten egg odour.
• $N{a}_{2}S$ is a yellow coloured flaky anhydrous compound.
• When $N{a}_{2}S$ reacts with HCl it gives Nacl and $H_{2}S$ gas.
• The recation is : $N{a}_{2}S\left(s\right)+2HCl\left(aq\right)\to 2NaCl\left(aq\right)+H_{2}O$
• The correct answer is both option C and D.