Question

Consider the following selected postulates of Dalton's atomic theory: (i) Each element is composed of extremely small particles called atoms. (ii) Atoms are indivisible. (iii) Atoms of a given element are identical. (iv) Atoms of different elements are different and have different properties. Which of the postulates is(are) no longer considered valid?
A) (i) and (ii)
B) (ii) only
C) (ii) and (iii)
D) (iii) only
E) (iii) and (iv)

Answer 1

Answer:

B)

Explanation:

Dalton was the first scientist to propose an atomic model. He said that each element is composed of extremely small particles called atoms, which are indivisible, atoms of a given element are identical, and atoms of different elements have different properties.

With the advance of the studies, it was proven that elements are composed of small particles, atoms and that the atoms of each element are identical, and have different properties from atoms of different elements.

But, now we know that the atom can be divisible: it's formed by electrons, protons, and neutrons. So only postulate ii is no longer considered valid.