Question

Enthalpy of formation is non zero for a] CO(g) [b]H2(g). C]O2(g). d]H+(aq)

Answer 1

Answer: The correct answer is (A) CO ( carbon monoxide).

Explanation:

The rest of the given options have a zero standard enthalpy of formation. It is because elements present in the standard states ( such as oxygen gas, hydrogen gas) do not undergo any change in their formation and are in their naturally occurring form.

Also, the enthalpy of formation for any ion is assigned zero. Since carbon monoxide is a compound that needs to be formed from the elements carbon and oxygen, therefore it involves the exchange of energy and enthalpy of formation is non zero.