Choose the correct nuclear-radiation statements: (I) Slow neutrons cause U-235 fission more effectively than fast neutrons. (II) α-rays are helium nuclei. (III) β-rays are fast electrons or positrons. (IV) γ-rays have wavelengths longer than X-rays.
Options

Question

Choose the correct nuclear-radiation statements: (I) Slow neutrons cause U-235 fission more effectively than fast neutrons. (II) α-rays are helium nuclei. (III) β-rays are fast electrons or positrons. (IV) γ-rays have wavelengths longer than X-rays.

Options

G1 Physics · Accepted Answer

(I) True: thermal neutrons have high fission cross section for U-235. (II) True: α particles are He-4 nuclei. (III) True: β⁻ are electrons, β⁺ are positrons. (IV) False: γ-rays generally occupy the shorter-wavelength, higher-energy region compared with ordinary X-rays (their energy ranges overlap). Final answer: Option A.