NEET Chemistry: State functions Practice Questions

Correct answer: D — Change in Enthalpy (ΔH)

When the process occurs at constant pressure, the heat exchanged is equal to the change in enthalpy (ΔH), which is defined as Qₚ = ΔH for pressure-volume work calculations.

Correct answer: A — Internal Energy (U)

A state function is a property that depends only on the current state of the system, not on the path taken to reach that state. Internal Energy (U), Enthalpy (H), Helmholtz Free Energy (A), and Entropy (S) are all examples of state functions. Work (W) and Heat (q) are path functions.

Correct answer: B — Work Done (W)

Work done (W) is a path function (it depends on the process taken), whereas internal energy (U) is a state function (it depends only on the initial and final states).

Correct answer: D — State Function

Entropy (S) is a state function. It describes the disorder or randomness of the system at a specific state, independent of how the system arrived at that state.

Correct answer: D — Change in Internal Energy

The change in Internal Energy (ΔU) is a state function. It is calculated using the initial and final states regardless of the specific path taken during the transformation.

Correct answer: A — ΔU = Q - W

For a closed process, the First Law of Thermodynamics states that the change in internal energy is equal to the heat supplied to the system plus the work done on the system (ΔU = Q + W).

Correct answer: C — Positive

For an isolated system (no heat or work exchange), the total entropy change must be zero according to the Second Law applied to isolated systems (or the entropy of the universe must increase). If the system is isolated, ΔS = 0 for the system itself.

Correct answer: B — G is the criterion for spontaneity of a process under constant temperature and pressure.

Gibbs Free Energy (G) is defined as G = H - TS. It is the criterion used to predict the spontaneity of a process when the process occurs at constant temperature and pressure, as defined by the Second Law of Thermodynamics.

Correct answer: D — Enthalpy

Enthalpy (H) is a state function. It depends only on the initial and final states of the system, not the process taken.

Correct answer: D — Negative (ΔG < 0)

For a process to be spontaneous (irreversible), the change in Gibbs Free Energy must be negative (ΔG < 0). A reversible process occurs when ΔG = 0.

Correct answer: A — Internal Energy

State functions (like internal energy, enthalpy, and entropy) depend only on the system's current state. Heat and work are path functions, dependent on the process taken.

Correct answer: D — Positive

The Second Law states that for a spontaneous process in an isolated system, the total entropy of the universe must increase, meaning ΔSᵤₙᵢᵥₑᵣₛₑ > 0.

Correct answer: A — ΔG must be negative

For a process occurring spontaneously under constant temperature and pressure, the change in Gibbs Free Energy (ΔG) must be negative (ΔG < 0). This is the fundamental thermodynamic criterion for spontaneity.

Correct answer: D — Zero

Since state functions depend only on the initial and final states, if the initial state equals the final state, the change in any state function (like energy) must be zero.

Correct answer: A — Negative

For a reversible and spontaneous process, the change in Gibbs free energy must be negative (ΔG < 0).