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Match the LIST-I with LIST-II
LIST-ILIST-II
A. ^1mathrmn + ^235_92mathrmU rightarrow ^140_54mathrmXe + ^94_38mathrmSr + 2^1_0mathrmnI. Chemical reaction
B. 2mathrmH_2 + mathrmO_2 rightarrow 2mathrmH_2mathrmOII. Fusion with +mathrmve Q value
C. ^2_1mathrmH + ^2_1mathrmH rightarrow ^3mathrmHe + ^1_0mathrmnIII. Fission
D. ^1_1mathrmH + ^3_1mathrmH rightarrow ^2_1mathrmH + ^2_1mathrmHIV. Fusion with -mathrmve Q value
Choose the correct answer from the options given below:

Solution & Explanation

### Related Formula - **Nuclear Fission**: Heavy nucleus splits into intermediate lighter fragments after absorbing a neutron. - **Nuclear Fusion**: Extremely light isotopes combine to form heavier nuclei. - **Q-value**: Positive for exothermic nuclear processes (releasing energy) and negative for endothermic nuclear processes (absorbing energy). ### Core Logic Let us check each reaction: - **Reaction A**: ^1mathrmn + ^235_92mathrmU rightarrow ^140_54mathrmXe + ^94_38mathrmSr + 2^1_0mathrmn This is a heavy Uranium nucleus absorbing a neutron and splitting into smaller fragments. This is the definition of **Nuclear Fission** (III). - **Reaction B**: 2mathrmH_2 + mathrmO_2 rightarrow 2mathrmH_2mathrmO This represents the combination of hydrogen and oxygen molecules to form water, which is a classic exothermic **Chemical reaction** (I). - **Reaction C**: ^2_1mathrmH + ^2_1mathrmH rightarrow ^3mathrmHe + ^1_0mathrmn Light Deuterium nuclei fuse together to form Helium-3, releasing considerable energy (Q > 0). This is **Fusion with positive Q value** (II). - **Reaction D**: ^1_1mathrmH + ^3_1mathrmH rightarrow ^2_1mathrmH + ^2_1mathrmH Proton and Tritium reacting to form Deuteron products. Since this reaction has products with a lower binding energy than the reactants, it is an endothermic process. Hence, it is **Fusion with negative Q value** (IV). ### Step 1: Alignment Let's summarize the matches: - A rightarrow III - B rightarrow I - C rightarrow II - D rightarrow IV This perfectly corresponds to Option (2). ### Pattern Recognition Identifying chemical vs. nuclear reactions is trivial (chemical reactions involve molecular change like 2mathrmH_2 + mathrmO_2, whereas nuclear reactions involve changes in nuclear isotopes). Always use chemical reactions to instantly lock in a match (B-I) and narrow down options! ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Nuclei Class 11 Chemistry: Chemical Bonding and Molecular Structure

Reference Study Guides

Nuclei

More Nuclei Previous-Year Questions

Q12 2025 Nuclear Fusion and Binding Energy
Energy released when two deuterons (_1mathrmH^2) fuse to form a helium nucleus (_2mathrmHe^4) is: (Given: Binding energy per nucleon of _1mathrmH^2 = 1.1 MeV and binding energy per nucleon of _2mathrmHe^4 = 7.0 MeV)
  • A. 8.1 \ mathrmMeV
  • B. 5.9 \ mathrmMeV
  • C. 23.6 \ mathrmMeV
  • D. 26.8 \ mathrmMeV

Solution

### Related Formula 1. Fusion reaction: _1mathrmH^2 + _1mathrmH^2 longrightarrow _2mathrmHe^4 2. Q-value (Energy Released) of a nuclear reaction: Q = textTotal Binding Energy (Products) - textTotal Binding Energy (Reactants) ### Core Logic Let's compute the total binding energies: - **Reactants:** Two deuterons (_1mathrmH^2). - Number of nucleons in each deuteron = 2 - Binding energy per nucleon = 1.1 \ mathrmMeV - Total Binding Energy of reactants: textBE_textreactants = 2 times [2 times 1.1 \ mathrmMeV] = 4.4 \ mathrmMeV - **Products:** One helium nucleus (_2mathrmHe^4). - Number of nucleons = 4 - Binding energy per nucleon = 7.0 \ mathrmMeV - Total Binding Energy of products: textBE_textproducts = 4 times 7.0 \ mathrmMeV = 28.0 \ mathrmMeV ### Step 1: Calculate energy released The energy released (Q) in the fusion process is: Q = textBE_textproducts - textBE_textreactants Q = 28.0 \ mathrmMeV - 4.4 \ mathrmMeV = 23.6 \ mathrmMeV Thus, the energy released is 23.6 \ mathrmMeV. ### Pattern Recognition Sees: Q-value of fusion from binding energy per nucleon. Trap: Confusing "Binding Energy per nucleon" with the total binding energy of the nucleus. Always multiply by the mass number A first! Shortcut: Q = (A_textfinal times textBE_textfinal) - (A_textinitial times textBE_textinitial) = (4 times 7.0) - (2 times 2 times 1.1) = 28 - 4.4 = 23.6 \ mathrmMeV. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Nuclei
Q12 2025 Radioactivity and Beta Decay
Choose the correct nuclear process from the below options [p: proton, n: neutron, mathbfe^- : electron, mathrme^+ : positron, v: neutrino, overlinenu : antineutrino]
  • A. mathrmnrightarrow mathrmp + mathrme^- + overlinemathrmv
  • B. mathfraknto mathfrakp + mathfrake^- + mathfrakv
  • C. mathrmnrightarrow mathrmp + mathrme^+ + overlinemathrmv
  • D. mathrmnrightarrow mathrmp + mathrme^+ + mathrmv

Solution

### Core Logic In basic beta^- emission processes, a neutron decays inside a nucleus to satisfy lepton numbers and conservation rules: mathrmn rightarrow mathrmp + mathrme^- + overlinenu ### Step 1: Conservation Cross-Check Charge Balance: 0 rightarrow (+1) + (-1) + 0 = 0 (Conserved) Lepton Family Index: 0 rightarrow 0 + (+1) + (-1) = 0 (Conserved via antineutrino entry). This perfectly isolates option (1). ### Pattern Recognition Negative beta emission is always accompanied by an antineutrino, whereas positive positron transformation releases a regular neutrino molecule. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Nuclei
Q1 2025 Radioactivity
A radioactive material P first decays into Q and then Q decays to non-radioactive material R. Which of the following figure represents time dependent mass of P, Q and R?
  • A.
  • B.
  • C.
  • D.

Solution

### Related Formula N = N_0 e^-lambda t where lambda is the decay constant. ### Core Logic Initially, only material P is present, so its mass decreases exponentially from a maximum value to zero. Material Q is formed from P and then decays into R, so its mass initially increases from zero, reaches a maximum, and then decreases to zero. Material R is stable and accumulated over time, so its mass increases continuously from zero and levels off at a maximum value equal to the initial mass of P. ### Step 1: Graphical Identification Looking at the options, option (2) correctly depicts the exponential decay of P, the transient rise and fall of Q, and the continuous growth of R to a stable value.
Radioactive decay curves for P, Q, and R
Radioactive decay curves for P, Q, and R
### Pattern Recognition For sequential decay P rightarrow Q rightarrow R, parent P always starts at max and drops to 0. Intermediate Q starts at 0, peaks, and returns to 0. Final stable product R starts at 0 and grows asymptotically to max value. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Physics: Nuclei

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