EVERYDAY SCIENCE

Detailed explanation-1: -The indivisibility of an atom was proved wrong: an atom can be further subdivided into protons, neutrons and electrons. However an atom is the smallest particle that takes part in chemical reactions.

Detailed explanation-2: -In short, Thomson had discovered the existence of particles smaller than atoms. This disproved Dalton’s claim that atoms are the smallest particles of matter.

Detailed explanation-3: -While controversial at first, Thomson’s discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton’s atomic theory that assumed atoms were indivisible.

Detailed explanation-4: -An atom is the smallest particle is incorrect as it can be divided into the subatomic particles of protons, neutrons, and electrons. An atom of the same element has the same mass and the shape is incorrect because some elements show different atoms having different masses (isotopes).

Detailed explanation-5: -Which part of Dalton’s atomic theory contradicts the existence of isotopes? According to one of the postulates of Dalton’s atomic theory, all atoms of an element have identical masses. This theory does not take into account isotopes, which are atoms of the same element having different atomic masses.