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Question

Chemistry Question on p -Block Elements

A crystalline solid XX reacts with dil.HCldil. HCl to liberate a gas Y.YY.Y decolourises acidified KMnO4KMnO_4. When a gas Z'Z' is slowly passed into an aqueous solution of YY, colloidal sulphur is obtained. XX and ZZ could be, respectively

A

Na2SO4,H2SNa_2SO_4,H_2S

B

Na2SO4,SO2Na_2SO_4,SO_2

C

Na2S,SO3Na_2S,SO_3

D

Na2SO3,H2SNa_2SO_3,H_2S

Answer

Na2SO3,H2SNa_2SO_3,H_2S

Explanation

Solution

Na2SO3(X)Na _{2} SO _{3}(X) reacts with dil. HClHCl to liberate SO2SO _{2} gas (Y)(Y).
This SO2SO _{2} gas decolourises acidified KMnO4.KMnO _{4} . On passing H2SH _{2} S gas (Z)(Z) into aqueous solution of SO2SO _{2} (i.e., H2SO3H _{2} SO _{3} ), colloidal sulphur is obtained.
Complete reactions are as follows

2KMnO4Purple+2H2O+5SO2(Y)K2SO4+2MnSO4Colourless+2H2SO4\underset{\text{Purple}}{2KMnO_4} + 2H_2O + \underset{(Y)}{5SO_2} \longrightarrow K_2SO_4 + \underset{\text{Colourless}}{2MnSO_4} + 2H_2SO_4
H2O+SO2(Y)H2SO3Aqueous solution of YH _{2} O +\underset{(Y)}{ SO _2} \longrightarrow \underset{\text{Aqueous solution of Y}}{H_2SO_3}
H2SO3+2H2S(Z)2S+3H2OColloidal sulphurH _{2} SO _{3}+\underset{(Z)}{2 H _{2} S} \longrightarrow \underset{\text{Colloidal sulphur}}{2 S +3 H _{2} O}