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BITSAT2009ChemistryThermodynamics (C)Actual

At 25^ C and 1 bar which of the following has a non-zero H _ f ^ ?

Options

  1. ABr ₂( )
  2. BC (graphite)
  3. CO ₃( ~g )
  4. DI ₂( ~s )

Correct answer

C. O ₃( ~g )

Step-by-step solution

Ozone is allotropic form of oxygen and is of higher energy (by 68 ~K Cal mol ⁻¹ ) than O ₂ . Hence it can not be taken as the reference in standard state.

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