Nuclei — Class 12 Physics NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 12 Physics chapter "Nuclei" — 5 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 12 Physics chapter "Nuclei" — 5 important questions with detailed answers for CBSE board exam preparation.
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Key Questions Covered:
- What is nuclear binding energy? Derive the expression and explain its signifi…
- Define half-life and decay constant. Derive the radioactive decay law.
- Carbon-14 has half-life 5730 years. A sample has activity 100 Bq. Find the nu…
- + 2 more questions in the full chapter
Solutions Summary:
| Question | Status |
|---|---|
| What is nuclear binding energy? Derive the expression and… | ✓ Solved |
| Define half-life and decay constant. Derive the radioacti… | ✓ Solved |
| Carbon-14 has half-life 5730 years. A sample has activity… | ✓ Solved |
Showing 3 of 5 questions
Q1: What is nuclear binding energy? Derive the expression and explain its significance.
Nuclear Binding Energy: Energy released when nucleons combine to form nucleus; also the energy required to completely separate a nucleus into individual nucleons.
Mass Defect:
Mass of separated nucleons > mass of nucleus
Δm = (Z × m_p + N × m_n) - M_nucleus
Where:
Z = number of protons
N = numb...
Q2: Define half-life and decay constant. Derive the radioactive decay law.
Half-life (T₁/₂): Time required for half of the nuclei in a sample to decay.
Decay Constant (λ): Probability per unit time that a nucleus will decay.
Relation: λ = 0.693/T₁/₂ = ln(2)/T₁/₂
Radioactive Decay Law Derivation:
Let N = number of nuclei at time t
Rate of decay proportional to number pre...
Q3: Carbon-14 has half-life 5730 years. A sample has activity 100 Bq. Find the number of C-14 nuclei and activity after 2000 years.
Given:
Half-life: T₁/₂ = 5730 years
Initial activity: A₀ = 100 Bq
Time elapsed: t = 2000 years
Part 1: Initial Number of Nuclei
Decay constant: λ = ln(2)/T₁/₂ = 0.693/5730 years
λ = 1.21 × 10⁻⁴ year⁻¹
Converting to seconds:
T₁/₂ = 5730 × 365.25 × 24 × 3600 = 1.808 × 10¹¹ seconds
λ = 0.693/(1.808 ×...
Showing 3 of 5 questions. Visit the full page for complete solutions.