Question

$FeS+HCl\to A+B\left(g\right)$

Gas $B$ is passed into aqueous solution of $C$ to form $A$. Select correct statements based on the above facts.

• A. Colour of $C$ changes from yellow to very light green
• B. Gas $B$ turns lead acetate paper black
• C. $A$ forms deep blue colour with $K_3\left[Fe\right(CN{)}_6]$
• D. All the above statements are correct

Answer 1

The correct option is D All the above statements are correct

$FeS+2HCl\to FeC{l}_2+H_{2}S$

gas A is = $Fe{Cl}_2$

gas B is = $H_{2}S$

C is $FeC{l}_3$ because
$FeC{l}_3+H_{2}S\to \underset{A}{FeC{l}_2}+Fe{S}_2+HCl$

$FeC{l}_3$ changes from yellow to very light green

$H_{2}S$ turns lead acetate paper black. The black colour is due to formation of lead sulphide (PbS).

and the $FeC{l}_3$ reacts with$K_3\left[Fe\right(CN{)}_6]$ and gives blue colour

$FeC{l}_2+K_3\left[Fe\right(CN{)}_6]\to \underset{\text{deep blue clour}}{F{e}_3\left[Fe\right(CN{)}_6{]}_2}+KCl$