Question

The Discovery of isotopes and isobars contradict some of the postulates of___________ atomic theory.

• A. Bohr's
• B. Dalton's
• C. Rutherford's
• D. Thomson's

Answer 1

The correct option is B

Dalton's

Dalton atomic theory:

Dalton put forward his atomic theory of matter. The various postulates (or assumptions) of Dalton’s atomic theory of matter are as follows:

• Matter consists of small indivisible particles called atoms.
• All atoms of an element are identical in nature.
• The atoms of an element are different from the atoms of any other element.
• A compound is formed by the combination of atoms of two or more elements in a simple ratio. The ratio between H and O in water is 2: 1 by volume.
• Atoms take part in chemical reactions.
• Atoms can neither be created nor be destroyed.

Merit:

• Dalton’s atomic theory explains the law of conservation of mass and the law of constant proportion.
• Atoms of elements take part in chemical reactions this is true today.

Demerit:

• The atom is no longer supposed to be indivisible.
• He could not explain why atoms of the same elements combined with each other.
• Atoms of the same element may not necessarily be identical in all aspects.- isotopes.
• Atoms of different elements may not necessarily be different in all aspects.- isobars.

Conclusion Statement: Option (b) is the correct answer.