How many of the following liberate coloured vapours/gas with concentrated H ₂ SO ₄ ? aligned & KCl ( s )+ K ₂ Cr ₂ O ₇( ~s ), KNO ₂( ~s ), KI ( s ), K ₂ ~S ( ~s ), KCl ( s ) & KBr ( s )+ MnO ₂( ~s ), KNO ₃( ~s ), KCl ( s )+ MnO ₂( ~s ), K ₂ SO ₃ aligned

Step-by-step solution

(i) 4 Cl ⁻+ Cr ₂ O ₇²⁻+6 H ⁺ 2 CrO ₂ Cl ₂ (deep red) +3 H ₂ O (ii) NO ₂⁻+ H ⁺ HNO ₂ ; 3 HNO ₂ HNO ₃+ NO +2 H ₂ O 2 NO + O ₂ NO ₂ (brown) (iii) 31⁻+2 H ₂ SO ₄ I ₃ ^ - (violet) + SO ₄ ²⁻+2 H ₂ O + SO ₂ (iv) K ₂ ~S + H ₂ SO ₄ H ₂ ~S (colourless) + K ₂ SO ₄ (v) Cl ⁻+ H ₂ SO ₄ HCl (colourless) + HSO ₄⁻ (vi) 2 KBr + MnO ₂+2 H ₂ SO ₄ Br ₂ ( reddish-brown )+2 ~K ⁺+ Mn ²⁺+2 SO ₄ ²⁻+2 H ₂ O (vii) KNO ₃+ H ₂ SO ₄ KHSO ₄+ HNO ₃ ; 4 HNO ₃ +2 H ₂ O + O ₂+4 NO ₂ (brown) (viii) 2 KCl + MnO ₂+3 H ₂ SO ₄ 2 KHSO ₄+ MnSO ₄+ Cl ₂ (yell