Match List – I with List – II.
| List - I | List - II | ||
|---|---|---|---|
| (A) | Alpha decay | (I) | \( {}^{32}_{15}\mathrm{P}\rightarrow{}^{32}_{16}\mathrm{S}+e^{-}+\bar{\nu}+\text{Energy} \) |
| (B) | Nuclear fission | (II) | \( {}^{2}_{1}\mathrm{H}+{}^{2}_{1}\mathrm{H}\rightarrow{}^{3}_{2}\mathrm{He}+{}^{1}_{0}n+\text{Energy} \) |
| (C) | Nuclear fusion | (III) | \( {}^{238}_{92}\mathrm{U}\rightarrow{}^{234}_{90}\mathrm{Th}+{}^{4}_{2}\mathrm{He}+\mathrm{KE} \) |
| (D) | Beta decay | (IV) | \( {}^{1}_{0}n+{}^{235}_{92}\mathrm{U}\rightarrow{}^{140}_{54}\mathrm{Xe}+{}^{94}_{38}\mathrm{Sr}+2\,{}^{1}_{0}n+\mathrm{KE} \) |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A)-(III), (B)-(IV), (C)-(II), (D)-(I)
Each process is recognised by what is emitted or what happens to the nucleus.
(A) Alpha decay — this matches (III) \( {}^{238}_{92}\mathrm{U}\rightarrow{}^{234}_{90}\mathrm{Th}+{}^{4}_{2}\mathrm{He}+\mathrm{KE} \). A helium nucleus \( {}^{4}_{2}\mathrm{He} \) (the alpha particle) is emitted, so Z falls by 2 and A by 4.
(B) Nuclear fission — this matches (IV) \( {}^{1}_{0}n+{}^{235}_{92}\mathrm{U}\rightarrow{}^{140}_{54}\mathrm{Xe}+{}^{94}_{38}\mathrm{Sr}+2\,{}^{1}_{0}n+\mathrm{KE} \). A neutron splits a heavy nucleus into two middle-mass fragments and releases more neutrons.
(C) Nuclear fusion — this matches (II) \( {}^{2}_{1}\mathrm{H}+{}^{2}_{1}\mathrm{H}\rightarrow{}^{3}_{2}\mathrm{He}+{}^{1}_{0}n+\text{Energy} \). Two light nuclei combine into a heavier one.
(D) Beta decay — this matches (I) \( {}^{32}_{15}\mathrm{P}\rightarrow{}^{32}_{16}\mathrm{S}+e^{-}+\bar{\nu}+\text{Energy} \). An electron and an antineutrino are emitted; A stays the same and Z rises by 1.
Note: Items (B) and (C) of this question, nuclear fission and nuclear fusion, are from the latest textbook (2026-27). Items (A) and (D), alpha decay and beta decay, are printed only in the pre-rationalised textbook (2022-23). They were removed from the latest book, and radioactive decay also appears to be out of the CUET 2026 syllabus.
NCERT (2026-27):
Fission – “… An example of fission is when a uranium isotope 23592U bombarded with a neutron breaks into two intermediate mass nuclear fragments … Or, as another example,
\( \displaystyle {}^{1}_{0}n + {}^{235}_{92}U \rightarrow {}^{140}_{54}Xe + {}^{94}_{38}Sr + 2\,{}^{1}_{0}n \qquad (13.12) \)”
Nuclear Fusion – Energy Generation in Stars – “When two light nuclei fuse to form a larger nucleus, energy is released, since the larger nucleus is more tightly bound, as seen from the binding energy curve in Fig.13.1.”
NCERT (Pre-rationalised edition, 2022-23):
Alpha Decay – “When a nucleus undergoes alpha-decay, it transforms to a different nucleus by emitting an alpha-particle (a helium nucleus, 42He). For example, when 23892U undergoes alpha-decay, it transforms to 23490Th”
Beta Decay – “… In beta minus (β–) decay, an electron is emitted by the nucleus, as in the decay of 3215P”