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#nucleus

12 public questions tagged with this topic.

Radioactive Decay, Nuclear Forces and Stability

What is the nuclear density of a nucleus with mass \( 3.67 \times 10^{-27} \, \text{kg} \) and radius \( 2.0 \times 10^{

**Stability** belt of stability N≈Z for light, N>Z for heavy due to Coulomb, beyond leads to alpha decay, fission, stability requires balance, nuclear force saturated explains constant density and BE/A. Density = (mass/volume) , Volume = (4/3) π R³ . R³ = (2.0 × 10⁻¹⁵)³ = 8.0 × 10⁻⁴⁵ m³ . Volume = (4/3) × 3.14 × 8.0 × 10⁻⁴⁵ ≈ 3.35 × 10⁻⁴⁴ m³ . Density = (3.67 × 10⁻²⁷/3.35 × 10⁻⁴⁴) ≈ 1.10 × 10¹⁷ kg/m³ . Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R = R₀ A^¹/³, BE = Δm c² and 1 u = 931.5

Ref: NCERT > Physics Book > Atoms and Nuclei > Radioactive Decay, Nuclear Forces and Stability

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Radioactive Decay, Nuclear Forces and Stability

Which force is responsible for overcoming the repulsion between protons in the nucleus?

**Nuclear force** strong, short-range ~1 fm, attractive, charge independent, saturated in large nuclei because each nucleon interacts only with neighbors, not all others, so BE/A saturates ~8 MeV, primary factor limiting stable nuclei size is Coulomb repulsion between protons growing as Z² vs strong force saturating, beyond Z≈83 no stable nuclei, competition between Coulomb and strong. The nuclear force, being much stronger than the Coulomb force, binds protons and neutrons together, overcoming the electrostatic repulsion between positively charged protons. Using E_n = -13.6/n² eV, r_n = n² a₀

Ref: NCERT > Physics Book > Atoms and Nuclei > Radioactive Decay, Nuclear Forces and Stability

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CHEMISTRY

What is the approximate ratio of the radius of an atom to its nucleus?

Rutherford’s model states the atomic radius is about 10⁻¹⁰m and the nuclear radius is 10⁻¹⁵m, giving a ratio of 10⁻¹⁰/ 10⁻¹⁵= __10POW₅__. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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Basics of Cell Biology

Which of the following is absent in prokaryotic cells?

Prokaryotes comprise bacteria and archaea lacking nucleus defined by nuclear envelope and possessing simpler architecture optimized for rapid division. They contain cell envelope with plasma membrane of phosphoglycerides and hopanoids, peptidoglycan wall providing shape and protection against turgor, nucleoid region where single circular chromosome typically 1-6 megabases supercoiled and organized by histone-like proteins HU, Fis, SMC condensins occupies cytoplasm without separation, and 70S ribosomes for coupled transcription translation. RNA species messenger, transfer, and ribosomal exist t

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 1: Prokaryotic vs Eukaryotic Organization.

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NMRSpectroscopy

How many spin states does a nucleus with I = 3/2 have?

Spin multiplicity follows rule 2I+1, counting magnetic sublevels mI ranging from -I to +I in integer steps. This quantization defines distinct energy states available for transition under radiofrequency irradiation. For I equals 3/2, allowed mI values are -3/2, -1/2, +1/2, +3/2, giving four orientational states. Such quadrupolar nuclei like 23Na, 35Cl exhibit line broadening due to electric quadrupole moment interaction. Understanding multiplicity explains spectral complexity of ions crucial for cellular electrolyte homeostasis, nerve conduction, and enzyme cofactor binding in biological conte

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Cell Signaling Dev Bio & Other Pathways

NICD translocates to nucleus and binds with

CSL/RBPJ, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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