Bohr's three postulates were introduced in 1913 as part of his atomic model, so option C is correct.

Planck's constant h is defined by E = h f, so E/f = h is Planck's constant.

Bohr radius r_n = n^2 r1, so r_10 = 100×0.53 Å = 53 Å; diameter = 2×53 Å = 106 Å.

Inverse beta decay is the primary known interaction used to detect neutrinos; the OCR shows a marker next to option C.

X-ray intensity decreases exponentially with thickness according to I = I0 e^{-μx}.

The strong nuclear force binds nucleons together, overcoming the electrostatic repulsion between protons.

Half-life T1/2 = mean-life × ln2 = 100 × 0.693 ≈ 69.3 s, so option D is correct.

Sodium-24 is commonly used as a tracer isotope to study blood circulation due to its suitable half-life and behavior in the body.

The SI unit of absorbed dose is the gray (Gy), equal to 1 joule per kilogram.

Mass decreases by 24 → 6 α-particles (6×4=24); atomic number decreases by 12 from α emissions (90→78) then increases by 4 β- decays to reach 82, so 6 α and 4 β.