In the wave-mechanical model, an orbital is a region of space in
an atom where there is(1) a high probability of finding an electron
(2) a high probability of finding a neutron
(3) a circular path in which electrons are found
(4) a circular path in which neutrons are found

The answer is (1). Quantum mechanics views electron orbitals not as fixed circular paths or defined boundaries, but as probablility distributions that represent the probability of finding an electron at any point in space around the nucleus. For simplicity, discrete "boundaries" are often drawn enclosing the area where electrons should be found 90% of the time.

The gas would begin to expand, and eventually the can would burst or explode.