How many of the following liberate coloured vapour/gas with concentrated `H_(2)SO_(4)`?
`KCl(s)+K_(2)Cr_(2)O_(7)(s), KNO_(2)(s),Kl(s), KBr(s),KCl(s)`
`KBr(s)+MnO_(2)(s),KNO_(3),KCl(s)+MnO_(2),K_(2)SO_(3)`

Answer

7

Explanation

`(i) 4Cl^(-)+Cr_(2)O_(7)^(2-)+6H^(+) to 2CrO_(2)Cl_(2) uarr ("deep red")+3H_(2)O`
`(ii) NO_(2^(0-))+H^(+) to HNO_(2), " " 3HNO_(2) to HNO_(3)+NO uarr +H_(2)O`
`2NO uarr +O_(2)uarr to NO_(2) uarr`(brown)
(iii) `3l^(-)+2H_(2)SO_(4) to l_(3^(-)) uarr ("violet") +SO_(4)^(2-)+2H_(2)O+SO_(2)`
`(iv)2KBr +2H_(2)SO_(4) to Br_(2) uarr ("reddish brown")+SO_(2) uarr+NO_(4)^(2-)+2K^(+)+2H_(2)O`
(v)` Cl^(-)+H_(2)SO_(4) to HCl uarr ("colourless")+HSO_(4^(-))`
`(vi) 2KBr+MnO_(2)+2H_(2)SO_(4) to Br_(2) uarr ("reddish-brown") +2K^(+) +Mn^(2+) +2SO_(4)^(2-)+2H_(2)O`
(vii) `4NO_(3^(-))+2H_(2)SO_(4) to NO_(2) uarr ("brown")`
(viii) `KCl+MnO(OH)_(2)+2H_(2)SO_(4) to Mn^(2+ +Cl_(2) uarr ("yellowish green") +2SO_(4)^(2-)+3H_(2)O`
(ix) `SO_(3)^(2-) +2H^(+) to SO_(2) uarr ("colourless")+H_(2)O`