Which are correct for a reversible reaction

Options

A. The reaction is never completed
B. These always attain equlibrium
C. At equilibrium only products are present
D. When the gaseous phase reaction is carried out in closed space, it attains equilibrium state after suitable time.

Answer

To determine which statements are correct for a reversible reaction, we will analyze each statement based on the principles of chemical equilibrium.

### Step-by-Step Solution:

1. **Understanding Reversible Reactions**:
- A reversible reaction is one that can proceed in both the forward and backward directions. For example, if we have a reaction A ⇌ B, A can convert to B and B can convert back to A.

**Hint**: Think about how reversible reactions differ from irreversible reactions in terms of directionality.

2. **Equilibrium in Reversible Reactions**:
- At equilibrium, the rates of the forward and backward reactions are equal. This means that the concentration of reactants and products remains constant over time.

**Hint**: Consider what happens to the concentrations of reactants and products when a system reaches equilibrium.

3. **Closed Vessel Requirement**:
- For gaseous reactions, they must be conducted in a closed vessel to prevent the escape of reactants or products, which could affect the equilibrium.

**Hint**: Reflect on why maintaining a closed system is crucial for the study of gaseous reactions.

4. **Presence of Reactants and Products at Equilibrium**:
- In a reversible reaction, both reactants and products are present at equilibrium. This is different from irreversible reactions, where only products are present once the reaction is complete.

**Hint**: Compare the outcomes of reversible and irreversible reactions at equilibrium.

5. **Completion of Reaction**:
- A reversible reaction never goes to completion; instead, it reaches a state of dynamic equilibrium where both reactants and products coexist.

**Hint**: Think about the implications of a reaction being reversible on its completion.

6. **Conclusions on the Statements**:
- **Statement 1**: The reaction is never completed. **(Correct)**
- **Statement 2**: They always attain equilibrium. **(Correct)**
- **Statement 3**: At equilibrium, only products are present. **(Incorrect)**
- **Statement 4**: When the gaseous phase reaction is carried out in a closed space, it attains equilibrium state after a suitable time. **(Correct)**

### Final Answer:
The correct statements regarding reversible reactions are:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect
- Statement 4: Correct

Thus, the correct options are 1, 2, and 4.