The following ideas were those underlying John Dalton's atomic theory, published in 1803.Which idea is known to be correct?

Explanation

The correct idea is that atoms are very small. This aligns with modern atomic theory, which recognizes atoms as the basic units of matter that are incredibly small and not visible to the naked eye. The notion that atoms are indivisible is incorrect, as modern science shows that atoms consist of smaller subatomic particles such as protons, neutrons, and electrons. The idea that atoms of an element are identical is also outdated, as isotopes of the same element can have different numbers of neutrons. Lastly, while atoms of different elements generally have different masses, there are exceptions, such as isotopes from different elements having similar masses.