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Sodium sulphite on heating with dilute HCl liberates a gas which

Option: 1

Turns lead acetate paper black


Option: 2

Turns acidified potassium dichromate paper green


Option: 3

Burns with a blue flame


Option: 4

Smells like vinegar


Answers (1)

best_answer

The given reaction is a test for suplhite ions. 

Upon reaction with dilute HCl it forms SO_2 as given below

Na_2SO_3 + 2\ HCl \longrightarrow SO_2 + 2\ NaCl +H_2O

SO_2 can be further detected by passing through acidified dichromate paper which turns green owing to the formation of Cr^{3+} ions.

K _{2} Cr _{2} O _{7}+ H _{2} SO _{4}+3 SO _{2} \longrightarrow K _{2} SO _{4}+\underset{(Green)} {Cr _{2}\left( SO _{4}\right)_{3}}+ H _{2} O

Hence, the correct answer is Option (2)

Posted by

Nehul

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