Question

The emission of β-particles is from 
1. the valence shell of an atom
2. the inner shell of an atom
3. the nucleus due to the nuclear conversion, neutron → proton + electron
4. the nucleus due to the nuclear conversion, proton → neutron + electron

Answer 1

Correct Answer - Option 3 : the nucleus due to the nuclear conversion, neutron → proton + electron

Concept:

• Beta particles (β) are high energy, high-speed electrons (β-) or positrons (β+) that are ejected from the nucleus by some radionuclides during a form of radioactive decay called beta-decay. 
• Beta-decay normally occurs in nuclei that have too many neutrons to achieve stability.

Explanation:

• Beta particles have a mass that is half of one-thousandth of the mass of a proton and carry either a single negative (electron) or positive (positron) charge.
• As they have a small mass and can be released with high energy.
• Beta minus particle (β-) emission occurs when the ratio of neutrons to protons in the nucleus is too high.
• An excess neutron transforms into a proton and an electron.
• The proton stays in the nucleus and the electron is ejected energetically, the conversion of a neutron to a proton actually changes the radionuclide to a different element.

• Often, gamma-ray emission accompanies the emission of a beta particle.
• When the beta particle ejection doesn't rid the nucleus of the extra energy, the nucleus releases the remaining excess energy in the form of a gamma photon.