Match List - I with List - II.
| List - I | List - II |
| (A) To slow down fast moving neutrons | (I) Thermal neutrons |
| (B) A neutron or a proton | (II) Fission |
| (C) Slow neutrons | (III) Moderator |
| (D) Neutron induced nuclear reaction | (IV) Nucleon |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A)-(III), (B)-(IV), (C)-(I), (D)-(II)
All four items come from the nucleus and the nuclear reactor, where slow neutrons split uranium nuclei.
(A) To slow down fast moving neutrons — this matches (III) Moderator. A moderator (water, heavy water or graphite) slows the fast neutrons released in fission by collisions with light nuclei.
(B) A neutron or a proton — this matches (IV) Nucleon. Protons and neutrons are the particles that make up a nucleus, and either of them is called a nucleon.
(C) Slow neutrons — this matches (I) Thermal neutrons. Neutrons slowed until their energy is about that of thermal motion (about 0.025 eV) are called thermal neutrons.
(D) Neutron induced nuclear reaction — this matches (II) Fission. In fission a neutron is absorbed by a heavy nucleus such as uranium-235, which then splits into two lighter nuclei.
Note: Items (B) and (D) of this question are from the latest textbook (2026-27). Item (A), that moderators slow down fast neutrons in a reactor, is printed only in the pre-rationalised textbook (2022-23). It was removed from the latest book, and it also appears to be out of the CUET 2026 syllabus.
NCERT (2026-27):
Atomic Masses and Composition of Nucleus – “… One also uses the term nucleon for a proton or a neutron.”
Fission – “… A most important neutron-induced nuclear reaction is fission.”
NCERT (Pre-rationalised edition, 2022-23):
Nuclear Reactor – “… Therefore, in reactors, light nuclei called moderators are provided along with the fissionable nuclei for slowing down fast neutrons.”