Can an electron reside inside the nucleus ?

Can an electron be emitted from the nucleus? Explain.

In atom, an electron is revolving around the nucleus. What is the work done?

The motion of an electron around the nucleus cannot be determined accurately. Account for this statement.

Assertion: The ionization of s-electrons requires more energy than that for the ionization of p-electrons in the same shell. Reason: s-electrons are closer to the nucleus than p-electrons and hence are more strongly attracted by nucleus.