Match List-I with List-II
| List-I | List-II |
| Nuclear decay/ Reaction | Particle (s) involved |
| (A) 22286Rn → 21884Po | (I) Neutron |
| (B) X + 23592U → 23692U; X is | (II) β+ particle |
| (C) 23490Th → 23492U | (III) α-particle |
| (D) 2211Na → 2210Ne | (IV) 2β− particles |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) – (III), (B) – (I), (C) – (IV), (D) – (II)
In every nuclear reaction the mass number A and the atomic number Z are conserved. Compare A and Z on the two sides to find the particle involved.
(A) \( {}^{222}_{86}\mathrm{Rn} \rightarrow {}^{218}_{84}\mathrm{Po} \) — this matches (III) α-particle. A falls by 4 and Z falls by 2, which is exactly an alpha particle \( {}^{4}_{2}\mathrm{He} \).
\( \displaystyle {}^{222}_{86}\mathrm{Rn} \rightarrow {}^{218}_{84}\mathrm{Po} + {}^{4}_{2}\mathrm{He} \)
(B) \( X + {}^{235}_{92}\mathrm{U} \rightarrow {}^{236}_{92}\mathrm{U} \) — this matches (I) Neutron. X must have A = 236 − 235 = 1 and Z = 92 − 92 = 0, which is a neutron.
\( \displaystyle {}^{1}_{0}\mathrm{n} + {}^{235}_{92}\mathrm{U} \rightarrow {}^{236}_{92}\mathrm{U} \)
(C) \( {}^{234}_{90}\mathrm{Th} \rightarrow {}^{234}_{92}\mathrm{U} \) — this matches (IV) 2β− particles. A is unchanged and Z rises by 2. Each β− decay turns a neutron into a proton, raising Z by 1 without changing A, so two β− particles are emitted.
\( \displaystyle {}^{234}_{90}\mathrm{Th} \rightarrow {}^{234}_{92}\mathrm{U} + 2\,{}^{0}_{-1}\mathrm{e} + 2\bar{\nu} \)
(D) \( {}^{22}_{11}\mathrm{Na} \rightarrow {}^{22}_{10}\mathrm{Ne} \) — this matches (II) β+ particle. A is unchanged and Z falls by 1: a proton has turned into a neutron and emitted a positron.
\( \displaystyle {}^{22}_{11}\mathrm{Na} \rightarrow {}^{22}_{10}\mathrm{Ne} + {}^{0}_{+1}\mathrm{e} + \nu \)
NCERT (2026-27):
Radioactivity – “… Three types of radioactive decay occur in nature : (i) α-decay in which a helium nucleus
\( \displaystyle {}^{4}_{2}\mathrm{He} \)
is emitted; (ii) β-decay in which electrons or positrons (particles with the same mass as electrons, but with a charge exactly opposite to that of electron) are emitted; …”
Fission – “… An example of fission is when a uranium isotope \( {}^{235}_{92}\mathrm{U} \) bombarded with a neutron breaks into two intermediate mass nuclear fragments
\( \displaystyle {}^{1}_{0}\mathrm{n} + {}^{235}_{92}\mathrm{U} \rightarrow {}^{236}_{92}\mathrm{U} \rightarrow {}^{144}_{56}\mathrm{Ba} + {}^{89}_{36}\mathrm{Kr} + 3\,{}^{1}_{0}\mathrm{n} \qquad (13.10) \)”