Question

Discoveries 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

The explanation for the correct option: (A)

1. According to Dalton's atomic theory, all the atoms of the same element are identical in all respects, but different from those of other elements.
2. But the discovery of isotopes shows that atoms of the same element can have different masses. The discovery of isotopes contradicts the above two postulates of Dalton's atomic theory.
3. Isobars are elements that have the same mass numbers but different atomic numbers. Thus, The discovery of isobars also contradicts the above two postulates of Dalton's atomic theory.

The explanation for the incorrect options:

(B) Discoveries of isotopes and isobars contradict some of the postulates of Dalton's atomic theory.

(C) Discoveries of isotopes and isobars do not contradict some of the postulates of Rutherford's atomic theory.

(D) Discoveries of isotopes and isobars contradict some of the postulates of Dalton's atomic theory, not Thomson's model

Hence, option (A) is correct - Discoveries of isotopes and isobars contradict some of the postulates of Dalton's atomic theory.