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)

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)

Quizplus · Accepted Answer

Postulates (ii) and (iii) are no longer considered valid because atoms can be divided into smaller particles (protons, neutrons, and electrons), and isotopes have shown that atoms of the same element can have different masses.

Consider the Following Selected Postulates of Dalton's Atomic Theory