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Alpha particles, which are the nuclei of ionized helium atoms containing two protons and two neutrons, are emitted by certain radioactive elements. What is the effect of the emission of one alpha particle and two beta particles on the atomic and mass numbers of an atom?

1. Atomic hydrogen is highly unstable and exists for only a brief moment before decaying.
2. Alpha particles, being helium nuclei with two protons and two neutrons, are released by radioactive nuclei.
3. Alpha particle streams, also called α-rays, cause significant ionization in gases they pass through and are quickly absorbed by materials.
4. The emission of one alpha particle decreases the atomic number by 2 and the mass number by 4, while the emission of two beta particles raises the atomic number by 2. Thus, the combined emission of one alpha and two beta particles reduces the mass number by 4.

Correct answer: The emission of one alpha particle decreases the atomic number by 2 and the mass number by 4, while the emission of two beta particles raises the atomic number by 2. Thus, the combined emission of one alpha and two beta particles reduces the mass number by 4.

Solution

Option D correctly describes the changes in atomic and mass numbers due to the emission of alpha and beta particles. Alpha emission decreases the atomic number by 2 and the mass number by 4, while two beta emissions increase the atomic number by 2, resulting in a net decrease of 4 in the mass number.

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