Ranking particles by increasing charge-to-mass ratio magnitude

Steps:

• Charges: α particle (+2e), proton p⁺ (+e), β⁻ particle (-e, magnitude e).
• Masses: α (4 u), p⁺ (1 u), β⁻ (≈ 1/1836 u).
• |r| values: α = 2e/4u = 0.5 e/u; p⁺ = e/1u = 1 e/u; β⁻ ≈ e/(1/1836 u) = 1836 e/u.
• Increasing |r| order for the three particles: α < p⁺ < β⁻.

Why B is correct:

• Lists p⁺ before β⁻, matching the step where |r|{p⁺} < |r|{β⁻} in the overall increasing sequence.

Why the others are wrong:

• A: α → β⁻ skips proton, omitting full order of all three particles.
• C: p⁺ → α reverses order since |r|_{p⁺} > |r|_α.
• D: γ (photon) has charge 0 and |r| ≈ 0, smaller than p⁺, so reverses order; also not one of the given particles.

Final answer: B