In the options given below, let `E` denote the rest mass energy of a nucleus and `n` a neutron. The correct option is:

Options

A. `E(._(92)^(236)U)gtE(._(53)^(137)I)+E(._39^(97)Y)+2E(n)`
B. `E(._(92)^(236)U)ltE(._(53)^(137)I)+E(._39^(97)Y)+2E(n)`
C. `E(._(92)^(236)U)ltE(._(56)^(140)Ba)+E(._36^(94)Kr)+2E(n)`
D. `E(._(92)^(235)U)=E(._(56)^(140)Ba)+E(._36^(94)Kr)+2E(n)`

Answer

To solve the question regarding the rest mass energy of a nucleus and a neutron, we will analyze the given information step by step.

### Step 1: Understand the Concepts
- **Rest Mass Energy (E)**: This is the energy equivalent of the mass of a particle or nucleus at rest, given by the equation \(E = mc^2\), where \(m\) is the mass and \(c\) is the speed of light.
- **Fission Process**: This is a nuclear reaction in which a heavy nucleus splits into smaller nuclei, releasing energy.

### Step 2: Analyze the Given Information
We are given that:
- The rest mass energy of uranium (U) is compared to the rest mass energies of iodine (I), uranium (U), and two neutrons (n).
- The expression can be represented as:
\[ E_U > E_I + E_U + 2E_n \]
where \(E_U\) is the rest mass energy of uranium, \(E_I\) is the rest mass energy of iodine, and \(E_n\) is the rest mass energy of a neutron.

### Step 3: Apply the Concept of Mass Defect
In a fission reaction:
- The mass defect (\(\Delta m\)) occurs because the total mass of the products (smaller nuclei and neutrons) is less than the mass of the original nucleus (uranium).
- The energy released in the fission process can be calculated using:
\[ E = \Delta m \cdot c^2 \]
- This means that the rest mass energy of the original heavy nucleus (uranium) is greater than the total rest mass energy of the products (iodine, uranium, and neutrons).

### Step 4: Evaluate the Options
- **Option A**: \(E_U > E_I + E_U + 2E_n\) — This is correct as explained above.
- **Option B**: \(E_U < E_I + E_U + 2E_n\) — This is incorrect because the original nucleus has more energy.
- **Option C**: \(E_U = E_I + E_U + 2E_n\) — This is also incorrect as it implies no energy is released.
- **Option D**: Any other statement that contradicts the above conclusions.

### Conclusion
The only correct option is **Option A**: \(E_U > E_I + E_U + 2E_n\).