Question

Which of the following substances have zero value for their standard enthalpy of
(a) O3
(b) H2O
(c) ZnO
(d) None of these.

Answer 1

c) zno

is the answer

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Answer 2

Answer:

For carbon, we take the graphite to be most stable form. we calculate standard enthalpies of carbon compounds with reference to graphite. So standard enthalpy is zero for graphite.