Consider the following reactions: NaCl + K ₂ Cr ₂ O ₇+ H ₂ SO ₄ ~A + KHSO ₄+ NaHSO ₄+ H ₂ O A + NaOH B + NaCl + H ₂ O B + H ₂ SO ₄+ H ₂ O ₂ C + Na ₂ SO ₄+ H ₂ O In the product ' C ', ' X ' is the number of O₂²⁻ units, ' Y ' is the total number oxygen atoms present and ' Z ' is the oxidation state of C r . The value of X+Y+Z is _ _ _ _ .

Step-by-step solution

Reaction 1: NaCl + K₂Cr₂O₇ + H₂SO₄ CrO₂Cl₂ (A, chromyl chloride) Reaction 2: CrO₂Cl₂ + 4NaOH Na₂CrO₄ + 2NaCl + 2H₂O , B = Na₂CrO₄ Reaction 3: Na₂CrO₄ + H₂SO₄ + H₂O₂ CrO₅ + Na₂SO₄ + H₂O C = CrO₅ or CrO(O₂)₂ (chromium peroxide, blue) Structure: one oxo group and two peroxide ( O₂²⁻ ) units X = number of O₂²⁻ units = 2 Y = total oxygen atoms = 5 Z = oxidation state of Cr: O²⁻(-2) + 2 O₂²⁻(-4) = -6 , so Cr = +6 X + Y + Z = 2 + 5 + 6 = 13