The standard gibbs free energy of formation of is zero. (a) h2o (l) (b) o (g) (c) i2 (s)

c. I₂ (s)

Explanation:

Gibbs free energy -

It is a thermodynamic quantity , which is given by the change in enthalpy minus the product of the change in entropy and absolute temperature.

i.e.,

ΔG is given as the change in gibbs free energy ( KJ )

ΔS is given as the change in entropy ( KJ /K )

ΔH is given as the change in enthalpy ( KJ )

T = temperature ( Kelvin ( K ))

ΔG = ΔH - TΔS

The sign of ΔG determines the reaction spontaneity , as

ΔG = negative , the reaction is spontaneous and

If ΔG = positive , the reaction is non spontaneous .

The standard free energy of formation will be zero , only for the compounds that are in their pure form ,

Hence, from the given option,

I₂ (s) is naturally found in solid state , therefore , ΔG = 0

the answer is symmetrical : )