For the reversible reaction.
`A(s)+B(g) Leftrightarrow C(g)+D(g), triangleG^(@)=-350kJ`
Which one of the following statement is true?

Options

A. The reaction is thermodynamically non-feasible
B. the entropy change is negative
C. Equilibrium constant is greater than one
D. The reaction should be instantaneous

Answer

To determine which statement is true regarding the reversible reaction \( A(s) + B(g) \leftrightarrow C(g) + D(g) \) with a given \( \Delta G^\circ = -350 \, \text{kJ} \), we will analyze the implications of the negative Gibbs free energy change and the characteristics of the reaction.

### Step-by-Step Solution:

1. **Understanding Gibbs Free Energy (\( \Delta G^\circ \))**:
- The Gibbs free energy change (\( \Delta G^\circ \)) indicates the spontaneity of a reaction. A negative \( \Delta G^\circ \) suggests that the reaction is spontaneous under standard conditions.

2. **Evaluating the First Statement**:
- The first statement claims that the reaction is thermodynamically non-feasible or non-spontaneous. Since \( \Delta G^\circ \) is negative (-350 kJ), this statement is **incorrect**.

3. **Evaluating the Second Statement**:
- The second statement asserts that the entropy change is negative. To evaluate this, we calculate the change in the number of moles of gas (\( \Delta n_g \)):
- Products: \( C(g) + D(g) \) = 2 moles of gas
- Reactants: \( B(g) \) = 1 mole of gas
- Therefore, \( \Delta n_g = 2 - 1 = 1 \) (which is positive).
- A positive \( \Delta n_g \) indicates an increase in entropy, making this statement **incorrect**.

4. **Evaluating the Third Statement**:
- The third statement claims that the equilibrium constant \( K \) is greater than 1. The relationship between \( \Delta G^\circ \) and the equilibrium constant is given by:
\[ \Delta G^\circ = -2.303RT \log K \]
- Since \( \Delta G^\circ \) is negative, this implies that \( \log K \) must be positive, which means \( K > 1 \). Thus, this statement is **correct**.

5. **Evaluating the Fourth Statement**:
- The fourth statement suggests that the reaction would be instantaneous. However, the speed of a reaction (kinetics) is independent of the Gibbs free energy change. Therefore, this statement is **incorrect**.

### Conclusion:
The only true statement among the options provided is that the equilibrium constant is greater than 1.