An unstable nucleus releases radiation in the form of a helium particle. What process is occurring?

• A. Alpha decay
• B. Positron emission
• C. Beta decay
• D. Gamma emission

Answer: (A)

Verified step by step guidance

1. Understand that the problem describes a nucleus releasing a helium particle, which is a specific type of nuclear radiation.
2. Recall that a helium particle emitted from a nucleus is also known as an alpha particle, consisting of 2 protons and 2 neutrons.
3. Recognize that the emission of an alpha particle from a nucleus is called alpha decay, a process that reduces the atomic number by 2 and the mass number by 4.
4. Differentiate alpha decay from other types of nuclear decay: beta decay involves emission of electrons or positrons, and gamma emission involves release of high-energy photons without changing the atomic number or mass number.
5. Conclude that since the nucleus emits a helium (alpha) particle, the process occurring is alpha decay.