Question

which atomic model states that it is impossible to know the exact location of electrons around the nucleus?
bohr model
dalton model
plum pudding model
electron - cloud model

Explanation:

The electron - cloud model is based on quantum mechanics. It describes electrons as probability distributions around the nucleus rather than in fixed orbits. According to this model, it's impossible to precisely know the location of an electron at any given time. The Bohr model has electrons in fixed orbits, the Dalton model is a very early model that doesn't deal with electron location in this sense, and the plum - pudding model has electrons embedded in a positive 'pudding' but doesn't address the uncertainty of electron location as the electron - cloud model does.

Answer:

electron - cloud model