Question

An inorganic salt when heated with concentrated `H_(2)SO_(4)` evolves a colourless pungent smelling gas but with concentrated `H_(2)SO_(4)` and `MnO_(2)` evolves a coloured pungent smelling gas which bleaches moist litmus paper.The coloured gas is:
A. `NO_(2)`
B. `Cl_(2)`
C. `Br_(2)`
D. `I_(2)`

Answer 1

Correct Answer - B
`Cl^(-)+H_(2)SO_(4) to HCl uarr ("colourless") +HSO_(4)^(-)`
`MnO(OH)_(2)+2H_(2)SO_(4)+2Cl^(-) to Mn^(2+) +Cl_(2) uarr ("yellowish green")+2SO_(4)^(2-)+3H_(2)O`
`Cl_(2)+H_(2)O to 2HCl+[O]`
`Cl_(2)` is a yellowish green gas which bleaches litmus paper by oxidation.