John Dalton believed which of the following about atoms?

Atoms are real even though they're invisible.

All atoms of a single substance are identical.

The atom could be divided into smaller parts.

Atoms of different substances differ by weight.

Dalton's Atomic Theory

1) All matter is made of atoms. Atoms are indivisible and indestructible.

2) All atoms of a given element are identical in mass and properties

3) Compounds are formed by a combination of two or more different kinds of atoms.

4) A chemical reaction is a rearrangement of atoms.