NEET Chemistry Enthalpy MCQ Question
Which combination of statements about enthalpy is correct?
(i) The enthalpy change for a reaction is path-dependent (ii) Enthalpy is a state function (iii) ∆H is used to determine heat changes (iv) Standard enthalpy of elements in their standard states is zero.
(i) Enthalpy is a path-dependent function (ii) ∆H can be negative for exothermic reactions (iii) Enthalpy change can be calculated using the sum of enthalpies of products and reactants (iv) All elements have a standard enthalpy of formation equal to one.
(i) Enthalpy is a state function (ii) The enthalpy of vaporization is always positive (iii) Standard enthalpy of formation for elements is zero (iv) Enthalpy changes can be equal to changes in internal energy.
(i) Standard enthalpy of formation is zero for all elements (ii) Enthalpy changes can be determined from calorimetry (iii) Enthalpy changes are independent of temperature (iv) ∆H is always positive for combustion reactions.
Correct Answer
Detailed Explanation
Enthalpy is indeed a state function, and it is true that the enthalpy of vaporization is always positive. Moreover, the standard enthalpy of formation for elements in their standard states is defined to be zero. However, enthalpy changes are not equal to changes in internal energy unless under specific conditions.
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