Question

Which postulate of the Dalton's atomuc theory was modified after the discovery of isotopes.​

Answer 1

atoms of different elements have different masses

atoms of the same element have same masses

Answer 2

According to postulates of Dalton's atomic theory...

Atoms of same element are identical in all Respects. However, after the discovery of isotopes,it was modified as : atoms of same element and may not be similar in all Respects.