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99 Percentile Qs Bank for JEE MainChemistryThermodynamics (C)

Which of the following substances has highest value of standard molar enthalpy of formation at (298 ~K ) ?

Options

  1. A( NaF ( s ) )
  2. B( NaCl ( s ) )
  3. C( NaBr ( s ) )
  4. D( Nal ( s ) )

Correct answer

A. ( NaF ( s ) )

Step-by-step solution

Higher the stability of a substance, higher will be its standard molar enthalpy of formation value, ( | _f H^ | ) Among the halides, ( F ⁻ )is smallest and ( I ⁻ )is largest in size. So, according to Fajan's rule, ( NaF ) is mostly ionic in nature. ( NaI < NaBr < NaCl < NaF ) ( ) Ionic nature ( ) Thermal stability So, ( NaF ) has highest value of ( | _f H^ | ).

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