The existence of isotopes violates one of the original ideas of dalton's atomic theory. which one?

Explanation:

One of the Dalton's postulates states that:

The atoms of same element are similar in the shape and the mass and other properties but different from atoms of other elements.

But the existence of isotopes violates this postulate because isotopes are the species which have same atomic number but different atomic mass. For example, carbon exist in three isotopes which are C-12, C-13 and C-14 and have different mass and some properties and is a contradiction of this postulate.

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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