Nuclear fission and nuclear fusion — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Nuclear fission is the process in which

• A. light nuclei combine into a heavier one
• B. an electron splits into photons
• C. a heavy nucleus splits into lighter nuclei
• D. a nucleus absorbs light without changing

Question 2 · difficulty L1 · understanding

Nuclear fusion is the process in which

• A. a heavy nucleus splits
• B. gamma photons become electrons only
• C. atoms chemically bond
• D. light nuclei combine to form a heavier nucleus

Question 3 · difficulty L2 · understanding

A fission chain reaction is sustained by

• A. neutrons released in one fission causing further fissions
• B. electrons emitted from atoms causing chemical reactions
• C. visible photons alone
• D. gravity between nuclei

Question 4 · difficulty L2 · application

The Sun's energy is primarily produced by

• A. nuclear fission of uranium
• B. nuclear fusion
• C. chemical combustion
• D. radio waves heating its core

Question 5 · difficulty L2 · understanding

Nuclear fission is the process in which

• A. a heavy nucleus splits into lighter nuclei with release of energy
• B. two light nuclei combine into a heavier nucleus
• C. an atom loses an electron
• D. a molecule dissociates into ions

Question 6 · difficulty L3 · application

Why are extremely high temperatures needed for controlled fusion?

• A. To remove all neutrons
• B. To make electric charge vanish permanently
• C. To give nuclei enough kinetic energy to overcome strong Coulomb repulsion sufficiently for the nuclear force to act
• D. To reduce the speed of light

Question 7 · difficulty L3 · application

A moderator in a thermal fission reactor is used mainly to

• A. absorb all neutrons permanently
• B. increase fuel temperature only
• C. convert neutrons into electrons
• D. slow down neutrons

Question 8 · difficulty L3 · application

Why can a fission chain reaction occur in fissile material?

• A. Neutrons released in one fission can trigger further fissions
• B. Every fission absorbs all neutrons permanently
• C. Fission produces only photons and no neutrons
• D. The nuclei become chemically reactive molecules

Question 9 · difficulty L3 · application

The enormous energy release in fusion of light nuclei is primarily associated with

• A. an increase in binding energy per nucleon and corresponding mass-energy release
• B. chemical bond formation only
• C. loss of all protons
• D. creation of energy without mass change

Question 10 · difficulty L4 · analysis

Control rods in a reactor regulate the chain reaction by

• A. absorbing neutrons
• B. producing extra neutrons
• C. reflecting all gamma rays
• D. increasing uranium mass number