Identifying particles with opposite electrical charges

Steps:

• Recall standard charges: proton (+1), electron (-1), positron (+1), antiproton (-1), beta minus (-1), beta plus (+1), alpha particle (+2), helium nucleus (+2).
• Evaluate option A: both particles are identical (+2 charge).
• Evaluate option B: antiproton (-1) and beta plus (positron, +1) have opposite signs.
• Evaluate options C and D: check for matching signs (both negative or both positive).

Why B is correct:

• Antiproton is the antiparticle of proton with opposite charge (-1e), while beta plus particle is positron with +1e charge, per particle physics definitions.

Why the others are wrong:

• A: Alpha particle and helium nucleus are the same (+2e charge).
• C: Beta minus particle and electron are both -1e charge.
• D: Positron and proton are both +1e charge.

Final answer: B