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NEET levelSingle correct optionDifficulty 1 of 3td003

Which of the following has a standard enthalpy of formation equal to zero at $298 K$ and $1 bar$ ?

A $Br X_{2} (g)$
B $Br X_{2} (l)$
C $I X_{2} (g)$
D $C$ (diamond)

Answer: B

The standard enthalpy of formation of an element in its most stable form at the stated temperature is zero. At

298 K

bromine is stable as a liquid, iodine as a solid and carbon as graphite, so only

Br X_{2} (l)

qualifies.

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