Size & Density of the Nucleus Challenge
25 NEET-standard questions on nuclear size from α-scattering, R = R₀A^(1/3), constant nuclear density, isotopes, isobars and isotones. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 13 · p. 309Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Radius lawR = R₀ A^(1/3)R₀ = 1.2 fm = 1.2×10⁻¹⁵ m. Cube root of A, then multiply.
VolumeV ∝ R³ ∝ AVolume (and mass) go as A, so density is constant
Nuclear densityρ ≈ 2.3×10¹⁷ kg m⁻³Same for all A; water is 10³, so nuclear matter is ~10¹⁴ times denser
Ratio of radiiR₁/R₂ = (A₁/A₂)^(1/3)R₀ cancels. Ratio r of radii means ratio r³ of A
Alpha scatteringClosest approach d ∝ 1/K (5.5 MeV: 4.0×10⁻¹⁴ m)Gives an upper limit on size; fast electrons give accurate sizes
Atom vs nucleusRadius ratio ≈ 10⁴, volume ratio ≈ 10⁻¹²Atom is mostly empty; nucleus holds >99.9% of the mass
Nuclide familiesIsotopes: same Z · Isobars: same A · Isotones: same N³H and ³He are isobars; ¹⁹⁸Hg and ¹⁹⁷Au are isotones
right first tryfixed after explanationstill to fix
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