Question

During a negative beta decay,

• A. An atomic electron is ejected
• B. An electron which is already present within the nucleus is ejected
• C. A neutron in the nucleus decays emitting an electron
• D. A proton in the nucleus decays emitting an electron

Answer 1

The correct option is C A neutron in the nucleus decays emitting an electron

In a beta minus decay process a neutron inside the nucleus converts into a proton and an electron and an antineutrino is created.
${}_6^{14}C{\to }_7^{14}N+e^{-}+\overline{v}$
In the above example a neutron converted into a proton thus the mass number wasn't altered but the atomic number was increased by one.
Also an electron and an antineutrino were created and emitted from the nucleus.
The other options are absurd. Also this electron can't be an atomic electron, it has to be created. Why?? Because a neutral particle (neutron) gets converted to a positively charged particle (proton).
This is breaking a very fundamental law. The law of charge conservation. So there has to be a negative particle produced in the process. And that's why it can't be an atomic electron but a new one. Also Nucleus don't have electrons normally hanging around in them. Why? Well it’s beyond the scope of the book. LOL. I so much wanted to say that. But yea to learn about it watch some videos lectures on quantum mechanics, it’s quite interesting.
Also proton converts to neutron in beta plus decay and in the process forms positron and a neutrino. Positron has same mass as electron but the opposite charge.