A sodium salt `(A)` is heated with cone. Sulphuric acid. The evolved gas truns moist litmus paper red and producess white fumes in contact with a glass rod moistened with ammonia solution. It also gives white precipitate when passed through `AgNO_(3)` solution. When the salt is heated with `MnO_(2)` and cone. `H_(2)SO_(4)`, a gas with an irritating smell is evolved which turns starch-iodide paper blue. Identify the salt and the gaseous product evolved from it. Explain your answer with relevant chemical equations.

Explanation

`{:(A+MnO_(2)+underset(conc.)(H_(2)SO_(4))rarr,"Gas with an irritating smell"),(,"produced truns strach-iodide"),(,"paper blue"):}`
Sodium salt `A` is `NaCl` :
`Nacl+underset(conc.)(H_(2)SO_(4))overset(Delta)(rarr)NaHSO_(4)+HCl_((g))`
`HCl` being acidic , turns moist litums paper red.
`HCl+NH_(3) rarr underset("White fumes")(NH_(4)Cl)`
`HCl+AgNO_(3) rarr underset("White ppt")(AgCI darr)+HNO_(3)`
`3NaCl+MnO_(2)+underset(conc.)(2H_(2)SO_(4)) rarr 2NaHSO_(4)+MnSO_(4)+2H_(2)O+Cl_(2)`
`Cl_(2)+2Kl rarr 2KCl+I_(2) uarr`
`I_(2)` turns starch-iodide paper blue due to the formation of starch -`I_(2)` adsorption complex.