Question

An acid radical (A) when treated with dil. H2SO4, a
colourless gas (B) comes out which is suffocating with
the smell of burning sulphur. Gas B when treated with
K2Cr207 acidified with dil. H2SO4, green colour
appeared. A and B are respectively​

Answer 1

Answer:

so3 2- and so2

Explanation:

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Answer 2

Acid radical A is sulfite $(SO_3^{2-})$and

Gas B is sulfur dioxide $(SO_2)$

Explanation:

• When dilute sulphuric acid is added to the acid radical A, a suffocating colorless gas with the smell of burning sulfur is evolved.

• It means the acid radical A is sulfite and the gas evolved is sulfur dioxide $SO_2$

$SO_3^{2-}(aq) + H_2SO_4(aq) \rightarrow SO_4^{2-}(aq) + H_2O(l) + SO_2(g)$

• Sulfur dioxide (Gas B) on reacting with potassium dichromate $(K_2Cr_2O_7)$ acidified with sulphuric acid, gives green color due to the formation of chromium sulfate which is green in color.

$K_2Cr_2O_7(aq) + H_2SO_4(aq) + 3SO_2(g)\rightarrow K_2SO_4(aq) + Cr_2(SO_4)_2(aq)+H_2O(l)$