This question got me thinking as to how close an electron can get to a nucleus. I thought that if it is possible to show that an electron can get closer to the nucleus than the value given in the question, then the answer would have no physical meaning.
What is the closest an electron can get to a nucleus?
Electrons and nuclei are described in the quantum mechanical regime, so the correct question is "what is the probability of an electron to overlap with a nucleus".
For electrons in a bound state around a nucleus,S level (angular momentum zero) electrons have a probability of overlapping the nucleus position. Proof is that Kcapture can happen in nuclear physics, when the energetics allows it .
This question got me thinking as to how close an electron can get to a nucleus.
The probability exists, and is non zero for scattering electrons on nucleons, and is energy dependent . If you take the trouble to read this link you will get the idea.
I am not addressing the question you are referring to.