The charge of an alpha particle can be neutralized by

Analyze the question: An alpha particle is a helium nucleus (⁴₂He), so it carries a charge of +2e. We need to find what neutralizes that charge.

Concept:

• Alpha particle: charge +2 (2 protons, 2 neutrons)
• Beta particle (β⁻): an electron, charge −1
• Gamma rays: photons of electromagnetic radiation, with no charge, so they cannot neutralize any charge

Solution: Total charge to cancel = +2e Each beta particle carries −1e

Number of beta particles needed = 2e ÷ 1e = 2

Gamma photons are neutral, so options B and E are wrong. One beta particle (A) only cancels half the charge. Four beta particles (D) would overshoot, leaving a net charge of −2e.

(Physically, an alpha particle neutralizes by picking up 2 electrons, becoming a neutral helium atom.)

Answer: C. 2 beta particles.

Tip: Remember the charges: alpha = +2, beta = −1, gamma = 0. To neutralize, just balance the charges, so +2 needs two −1 charges.