Educational worksheet on nuclear fission and fusion with fill-in-the-blank questions and a reaction diagram.

Let's go through the task step by step and solve it.

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Task: Identify whether each description refers to *Fission* or *Fusion*.

We are given 12 statements, and we need to classify each as Fission or Fusion. Then, there is a nuclear equation at the end (Question 13) that we must identify as either fission or fusion and explain why.

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Definitions Recap:

- Nuclear Fission: A heavy nucleus splits into two lighter nuclei, releasing energy. Often involves neutrons and can lead to chain reactions.
- Nuclear Fusion: Two light nuclei combine to form a heavier nucleus, releasing energy. Requires extremely high temperatures (like in stars).

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Now, let’s analyze each statement:

1. Requires at least two smaller atoms to enter
→ This describes fusion, where small nuclei combine.
✔ Fusion

2. The splitting of a large nucleus into smaller nuclei
→ This is the definition of fission.
✔ Fission

3. Usually occurs with light elements
→ Light elements fuse together (e.g., hydrogen in stars).
✔ Fusion

4. Unstable 235 U struck by a neutron, releasing energy
→ Uranium-235 is a heavy nucleus; when hit by a neutron, it undergoes fission.
✔ Fission

5. Usually starts with a heavy element
→ Fission begins with heavy elements like uranium or plutonium.
✔ Fission

6. Releases the most energy of the nuclear reactions
→ Both release energy, but fusion releases more energy per unit mass than fission.
✔ Fusion

7. Often leads to a chain reaction effect
→ Fission reactions can be self-sustaining via chain reactions (neutrons trigger more fissions).
✔ Fission

8. Requires at least one heavy nucleus to start
→ Fission requires a heavy nucleus (like U-235).
✔ Fission

9. The source of energy in stars like the Sun
→ Stars generate energy via fusion (hydrogen → helium).
✔ Fusion

10. Used to generate energy in nuclear power plants
→ Power plants use fission of uranium or plutonium.
✔ Fission

11. Generates nuclear waste that must be stored or buried
→ Fission produces radioactive waste; fusion does not produce long-lived waste.
✔ Fission

12. Not currently utilized as an energy source for humans
→ Fusion is not yet harnessed for practical energy production (still experimental).
✔ Fusion

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Question 13:

> $$
> {}_{92}^{235}\text{U} + {}_0^1\text{n} \rightarrow {}_{56}^{141}\text{Ba} + {}_{36}^{92}\text{Kr} + 3{}_0^1\text{n}
> $$

This equation shows:
- A uranium-235 nucleus absorbing a neutron.
- Splitting into barium (Ba) and krypton (Kr), along with three neutrons.
- This is nuclear fission because a heavy nucleus splits into lighter nuclei.

✔ Answer: Fission

Explanation:

This is a classic example of nuclear fission. The uranium-235 nucleus absorbs a neutron, becomes unstable, and splits into two smaller nuclei (barium and krypton), releasing additional neutrons and a large amount of energy. This process is used in nuclear reactors and atomic bombs.

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✔ Final Answers:

| Number | Description | Answer |
|--------|-------------|--------|
| 1 | Requires at least two smaller atoms to enter | Fusion |
| 2 | The splitting of a large nucleus into smaller nuclei | Fission |
| 3 | Usually occurs with light elements | Fusion |
| 4 | Unstable 235 U struck by a neutron, releasing energy | Fission |
| 5 | Usually starts with a heavy element | Fission |
| 6 | Releases the most energy of the nuclear reactions | Fusion |
| 7 | Often leads to a chain reaction effect | Fission |
| 8 | Requires at least one heavy nucleus to start | Fission |
| 9 | The source of energy in stars like the Sun | Fusion |
| 10 | Used to generate energy in nuclear power plants | Fission |
| 11 | Generates nuclear waste that must be stored or buried | Fission |
| 12 | Not currently utilized as an energy source for humans | Fusion |
| 13 | Equation: $ {}_{92}^{235}\text{U} + {}_0^1\text{n} \rightarrow {}_{56}^{141}\text{Ba} + {}_{36}^{92}\text{Kr} + 3{}_0^1\text{n} $ | Fission — because a heavy nucleus splits into lighter ones, releasing neutrons and energy. |

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Let me know if you'd like a visual diagram or further explanation!