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The nuclear radius of hydrogen atom will be ________.

Asked in GUJCET 2026 · Nuclear radius and density

• (1) 1.5 fm
• (2) 2.3 fm
• (3) 1.2 fm
• (4) 3.2 fm

Step-by-step solution

Why the other options are wrong

• (1) 1.5 fm takes the constant R₀ as 1.5 fm. The value used throughout the syllabus is R₀=1.2 fm, and with A=1 the radius is exactly R₀.
• (2) The figure 2.3 belongs to the density of nuclear matter, 2.3×10¹⁷ kg m⁻³, and not to any radius.
• (4) 3.2 fm is the radius of a nucleus with A=((3.2)/(1.2))³≈19 — fluorine, say. Hydrogen has A=1.

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