X( ~s ) dil HCl Y [ Na ₃ ( Fe ( CNO )₃( NO ) ] . Purple solution Gas Y has been allowed to react with following Biack species in neutralacidic medium (A) FeCl ₃ (B) CuSO ₄ (C) BaCl ₂ (D) SO ₂ (E) Cr ₂ O ₇²⁻ (F) CH ₃ COONa ⁻ (G) Hg ²⁺ Then calculate value of ( P + Q - R ) P : Number of species which undergoes redox reaction with gas Y Q : Number of species which give black ppt with gas Y P : Number of species with whi

Step-by-step solution

(a) 2 FeCl ₃+2 H ₂ ~S [ Nevicil ] Acitic 2 Fe ²⁺+ S +4 H ⁺+6 Cl ⁻ (b) CuSO ₄+ H ₂ ~S [ Nentral ] Acidicl Black CuS ₁ +2 H ⁺+ SO ₄²⁻ (c) BaCl ₂+ H ₂ ~S [ Neatral ] Acidc No observable charge Ba ²⁺ +2 Cl ⁻+2 H ⁺+ S ²⁻ (d) SO ₂ +2 H ₂ ~S 2 ~S + H ₂ O or SO ₂ + H ₂ O H ₂ SO ₃ H ₂ ~s ~S + H ₂ O (e) Cr ₂ O ₇²⁻+8 H ⁺+3 H ₂ ~S [ Nentril ] Andol 2 Cr ³⁺+ S +7 H ₂ O (g) Hg ²⁺+ H ₂ ~S [ Neveltal ] Acede Back HgS +2 H ⁺ P=3 ; Q=2 ; R=2 Hence value of (P+Q-R)=3+2-2=3