described atoms as having a positive nucleus with electrons that have different energies at different distances from the nucleus.
Option that go in the blank:
Bohr or Dalton or Rutherford or Thomson pick one

Niels Bohr

Explanation:

Niel’s Bohr described the atomic model. He in his model showed that an atom is a small positively charged nucleus. Around the positively charged nucleus, electrons orbit in separate orbits.  

The electrons in the outermost shell are responsible for the  properties associated with an element.  

The electrons at different shells have different energy. When an electron jumps from a shell of higher energy to a shell of lower energy, energy is released.  

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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