For the reaction A + B → C + D, ΔH° = +40 kJ and ΔS° = +50 J/K. Therefore, the reaction under standard conditions is: A) spontaneous only at temperatures between 10 K and 800 K. B) spontaneous at temperatures greater than 800 K. C) nonspontaneous at all temperatures. D) spontaneous at all temperatures. E) spontaneous at temperatures less than 10 K.

spontaneous at temperatures greater than 800 K.

Explanation:

From the thermodynamic equation ,

ΔG = ΔH - TΔS

For spontaneous reaction ΔG = - ve

ΔH - TΔS < 0

TΔS > ΔH

T > ΔH / ΔS

> 40000 / 50

> 800 K

At temperature greater than 800K , reaction will be spontaneous.

most of them using statistics and defining how things are being measured

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