Question

which of Dalton`s five statements is no longer treu based on the modern atomic theroy

Answer 1

Atoms cannot be created, destroyed, or subdivided.

J. J. Thomson (1856–1940) discovered that atoms are not indivisible. When excited by means of an electrical current, atoms break down into two parts. One of those parts is a tiny particle carrying a negative electrical charge, the electron.

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Answer 2

The full statement of that principle is 'Atoms cannot be created, destroyed or subdivided in the chemical process.' Maybe ionisation violates that principle, I'm not sure.
Nuclear reactions are all about the transformation of one kind of atom into another, but they are not regarded as chemical processes.
The principle that has definitely fallen by the wayside is 'All atoms of a given element are identical' because we now know that a single chemical element can exist in several varieties know as isotopes.
Isotopes of the same element have the same number of protons in the atomic nucleus, but different numbers of neutrons.