Nuclear Fission Basics: Understand Atomic Energy Release

1. Nuclear fission is:

Combining two light nuclei

Splitting a heavy nucleus into smaller nuclei

Rearranging electrons

Breaking chemical bonds

Fission splits a heavy nucleus into smaller nuclei. This is a nuclear change in the nucleus, not a change in electron arrangement or chemical bonding.

Explanation

Fission splits a heavy nucleus into smaller nuclei. This is a nuclear change in the nucleus, not a change in electron arrangement or chemical bonding.

2. Fission can release a large amount of energy.

True

False

Energy comes from changes in nuclear binding energy. The products are often more tightly bound, and the difference appears as released energy.

Explanation

Energy comes from changes in nuclear binding energy. The products are often more tightly bound, and the difference appears as released energy.

3. A common trigger for fission in reactors is a:

Proton

Electron

Neutron

Gamma ray

Neutrons have no charge and can enter the nucleus more easily. Charged particles are repelled by the positively charged nucleus, but neutrons are not.

Explanation

Neutrons have no charge and can enter the nucleus more easily. Charged particles are repelled by the positively charged nucleus, but neutrons are not.

4. In fission, the nucleus splits into two smaller ______ plus extra neutrons.

The products are new nuclei (fission fragments). These fragments are usually different isotopes/elements compared with the original nucleus.

Explanation

The products are new nuclei (fission fragments). These fragments are usually different isotopes/elements compared with the original nucleus.

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5. Why are neutrons useful for causing fission?

They are positively charged

They are negatively charged

They have no electric charge

They are made of light

No charge means no electrostatic repulsion barrier. That makes it easier for a neutron to be absorbed by a nucleus and trigger fission.

Explanation

No charge means no electrostatic repulsion barrier. That makes it easier for a neutron to be absorbed by a nucleus and trigger fission.

6. Fission often releases 2 or 3 neutrons that can cause more fissions.

True

False

These neutrons can sustain a chain reaction. If enough of them cause new fissions, the process can continue on its own.

Explanation

These neutrons can sustain a chain reaction. If enough of them cause new fissions, the process can continue on its own.

7. A 'chain reaction' means:

Electrons form chains

One fission leads to more fissions

A nucleus becomes stable instantly

Heat turns into mass

Neutrons from one fission can trigger others. The 'chain' is the repeated sequence of fission → neutrons → more fission.

Explanation

Neutrons from one fission can trigger others. The 'chain' is the repeated sequence of fission → neutrons → more fission.

8. In a power reactor, the main purpose is to use fission heat to:

Make light directly

Produce steam to turn turbines and generate electricity

Freeze water

Make metals magnetic

Heat → steam → turbine → electricity. The reactor is mainly a heat source, and the power station converts that heat into electrical energy.

Explanation

Heat → steam → turbine → electricity. The reactor is mainly a heat source, and the power station converts that heat into electrical energy.

9. Fission is a nuclear process, not a chemical process.

True

False

It involves the nucleus, not electron bonding. Chemical reactions rearrange electrons between atoms, while fission changes the nucleus itself.

Explanation

It involves the nucleus, not electron bonding. Chemical reactions rearrange electrons between atoms, while fission changes the nucleus itself.

10. The pieces formed after fission are called:

Photons

Fission fragments

Electrons

Molecules

The split nuclei are 'fragments.' They are smaller nuclei that typically carry lots of kinetic energy and may be radioactive.

Explanation

The split nuclei are 'fragments.' They are smaller nuclei that typically carry lots of kinetic energy and may be radioactive.

11. The total mass of products is slightly less than reactants, and the 'missing' mass becomes ______.

The small mass defect is converted into energy according to E=mc^2.

Explanation

The small mass defect is converted into energy according to E=mc^2.

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12. Which statement is correct?

Fission always absorbs energy

Fission can release energy because products are more tightly bound

Fission only changes electrons

Fission creates energy from nothing

Binding energy differences release energy. The products can have higher binding energy per nucleon, and the difference appears as released energy (not 'created from nothing').

Explanation

Binding energy differences release energy. The products can have higher binding energy per nucleon, and the difference appears as released energy (not 'created from nothing').

13. Energy released in fission appears mostly as kinetic energy of fragments and radiation.

True

False

Products fly apart fast; gamma rays may be emitted. Their kinetic energy is later converted to heat as they slow down in the fuel.

Explanation

Products fly apart fast; gamma rays may be emitted. Their kinetic energy is later converted to heat as they slow down in the fuel.

14. A material that can undergo fission easily with slow neutrons is called:

Elastic

Fissile

Insulating

Transparent

'Fissile' materials sustain chain reactions. They can fission after absorbing slow (thermal) neutrons, making them useful for many reactors.

Explanation

'Fissile' materials sustain chain reactions. They can fission after absorbing slow (thermal) neutrons, making them useful for many reactors.

15. Which are typical results of fission?

Two smaller nuclei

Neutrons released

Energy released

Oxygen gas produced

A–C are typical; oxygen gas is not a direct nuclear product. Fission produces nuclei, neutrons, and energy, not chemical gases like O₂.

Explanation

A–C are typical; oxygen gas is not a direct nuclear product. Fission produces nuclei, neutrons, and energy, not chemical gases like O₂.

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16. A reactor must control the chain reaction to be safe and useful.

True

False

Uncontrolled reactions are dangerous. Controlled reactions keep the power level steady and prevent overheating or rapid increases in reaction rate.

Explanation

Uncontrolled reactions are dangerous. Controlled reactions keep the power level steady and prevent overheating or rapid increases in reaction rate.

17. Fission of heavy nuclei is most strongly connected with:

The strong nuclear force and binding energy

The nucleus becoming more stable by splitting

The colour of the metal

Sound waves

Splitting can move products toward greater stability. This is explained using binding energy and the balance of forces in the nucleus, not colour or sound.

Explanation

Splitting can move products toward greater stability. This is explained using binding energy and the balance of forces in the nucleus, not colour or sound.