I = I₀ e^(-μx) for intensity of γ-rays after passing through material thickness x.

• The scoring line in Alpha Decay is: ~90% of 2500 known nuclides are radioactive/unstable.
• For Alpha Decay, first verify the condition hidden in the wording: Helium nucleus or doubly ionized helium atom (₂He⁴). Emitted when unstable nuclei decay.. That check tells you whether the question is asking for an observation, a consequence, or a limitation.
• Trap in Alpha Decay: students often replace it with Emitted by nuclei too large to be stable. Keep the exact subtopic statement separate from nearby atomic or nuclear ideas before eliminating options.

I = I₀ e^(-μx) for intensity of γ-rays after passing through material thickness x.

• The scoring line in Beta Decay is: β⁻ decay occurs when N/Z ratio too large for stability.
• For Beta Decay, first verify the condition hidden in the wording: Fast moving electron (not orbital electron; comes from nuclear neutron decay).. That check tells you whether the question is asking for an observation, a consequence, or a limitation.
• Trap in Beta Decay: students often replace it with In β⁻ decay: N decreases by 1, Z increases by 1, A unchanged. Keep the exact subtopic statement separate from nearby atomic or nuclear ideas before eliminating options.

I = I₀ e^(-μx) for intensity of γ-rays after passing through material thickness x.

• The scoring line in Gamma Decay is: Nuclear excitation energies typically ~1 MeV (compared to atomic ~eV).
• For Gamma Decay, first verify the condition hidden in the wording: Photon emitted when nucleus in excited state decays to ground state. Typical energies 10 keV to 5 MeV.. That check tells you whether the question is asking for an observation, a consequence, or a limitation.
• Trap in Gamma Decay: students often replace it with Nucleus in excited state from bombardment or radioactive transformation. Keep the exact subtopic statement separate from nearby atomic or nuclear ideas before eliminating options.