`U-235` can decay by many ways , let us here consider only two ways, `A` and `B`. In decay of `U-235` by means of `A`, the energy released per fission is `210 MeV` while in `B` it is `186 MeV`. Then , the uranium `235` sample is more likely to decay by .

Options

A. scheme `A`
B. scheme `B`
C. equally likely for both schemes
D. it depends on half-life of schemes A and `B`

Explanation

To determine which decay mode of Uranium-235 (U-235) is more likely, we will analyze the energy released in each decay process.

### Step-by-Step Solution:

1. **Identify the Energy Released in Each Decay Mode**:
- For decay mode A, the energy released per fission is given as **210 MeV**.
- For decay mode B, the energy released per fission is given as **186 MeV**.

2. **Compare the Energy Released**:
- We compare the two values:
- Energy released in decay A: **210 MeV**
- Energy released in decay B: **186 MeV**
- Since **210 MeV** (A) is greater than **186 MeV** (B), we can conclude that decay mode A releases more energy.

3. **Understand the Implications of Energy Release**:
- In nuclear fission, a higher energy release typically indicates that the resulting nuclei are more stable. This is because the fission process tends to produce lighter and more stable nuclei from a heavier nucleus.
- Therefore, the decay mode that releases more energy is more favorable.

4. **Conclusion**:
- Since decay mode A releases more energy than decay mode B, we conclude that the Uranium-235 sample is more likely to decay by **decay mode A**.

### Final Answer:
The Uranium-235 sample is more likely to decay by **decay mode A**.

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