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The standard reduction potential data at 25^ C is given below. aligned & E ^ ( Fe ³⁺ . Fe ²⁺ )=+0.77 ~V ; & E ^ ( Fe ²⁺ . Fe )=-0.44 ~V ; & E ^ ( Cu ²⁺ . Cu )=+0.34 ~V ; & E ^ ( Cu ⁺ . Cu )=+0.52 ~V ; & E ^ ( O ₂( ~g )+4 H ⁺+4 e ⁻ 2 H ₂ O )=+1.23 ~V ; & E ^ ( O ₂( ~g )+2 H ₂ O +4 e ⁻ 4 OH ⁻ )=+0.40 ~V & E ^ ( Cr ³⁺ . Cr )=-0.74 ~V ; & . E ^ ( Cr ²⁺ . Cr )=-0.91 ~V ) aligned Which of the following statements is/are co

Options

  1. AO ₂ is a better oxidising agent in acidic medium.
  2. BCr ²⁺ show disproportionation to Cr and Cr ³⁺ in water.
  3. CO ₂ oxidises Fe ²⁺ to Fe ³⁺ in acidic medium.
  4. DCu ⁺ oxidises Fe to Fe ²⁺ and H ₂ O to O ₂ in acidic medium.

Correct answer

C. O ₂ oxidises Fe ²⁺ to Fe ³⁺ in acidic medium.

Step-by-step solution

(A) As E _ O ₂ / H ₂ O ; H ⁺ ^ E _ O ₂ / OH ⁻ ^ So, O ₂ is better oxidising agent in acidic medium. (B) 3 Cr ²⁺ 2 Cr ³⁺+ Cr aligned & x 1+2(-0.91)=-0.74 3 & x =-2.22+1.82=-0.40 ~V & E _ cell ^ = E _ Cr ²⁺ / Cr ^ - E _ Cr ³⁺ / Cr ²⁺ ^ &=-0.91-(-0.40) &=-0.51 ~V aligned As this is negative, So reaction is non spontaneous. (C) As SRP of O ₂ in acidic medium is more than SRP of Fe ³⁺ So, O ₂ oxidises Fe ²⁺ to Fe ³⁺ . (D) As SRP of Cu ⁺ / Cu is more than SRP of Fe ²⁺ / Fe , Cu ⁺ oxidises Fe . But SRP of Cu ⁺ / Cu is les

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