Question

One of the important shortcomings of the Bohr model of the atom was that:

it did not distinguish between protons and electrons

it specified both definite location and momentum (energy) for an electron

it showed that all electrons have equal energies

electron energies cannot be calculated

Answer 1

The second. The Bohr model is semiclassical (because it was constructed before quantum mechanics). The orbits of the electrons are restricted, however you stll have a classical orbit, in which the position and momentum of the electron are simultaneously knowable.

Quantum mechanics denies this is possible. If the orbit has a precise known angular momentum (which is generally that in which you're interested, because orbits with a known angular moment and energy are stable), then you give up a great deal of knowledge of exactly where the electron is at any given moment. You are forced to describe the location of the electron in terms of probability: it has an 80% chance of being within this distance of the atom, it has a 5% chance of being over here, et cetera.

You can, of course, choose to know exactly where the electron is at any given instance of time. But in that case, you lose the ability to know its angular momentum and energy, and, generally speaking, you won't know what its angular momentum and energy are a little while later, or what they were a little while ago. This is particularly unhelpful if you're trying to understand, say, atomic spectra.