Which was a testable idea that j. j. thomson developed through his experiments?

atoms are the most important substances in the universe.
it is impossible to divide an atom into smaller parts.
there are electrically neutral particles inside atoms.
atoms contain small, negatively charged particles.

The correct statement is atoms contain small, negatively charged particles.

Explanation:

J.J.Thomson was a scientist which discovered electrons that are present in an atom.

He did an experiment and gave a model for this. The experiment conducted by him was Cathode Ray experiment and the model given by him was Plum pudding model.

From cathode ray, he showed that the cathode ray was composed of a negatively charged particles and named it as electrons. From plum pudding experiment, he said that the electrons are embedded in the atom. These particles carry negative charge and are very small as compared to the atom.

Hence, the correct statement is atoms contain small, negatively charged particles.

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.