Which activity is the best demonstration of j. j. thomson’s use of creativity in his work?
-making observations in his experiment
- interpreting the results of his experiment
- assembling the apparatus for his experiment
- taking notes on joseph proust’s work

Explanation:

Interpreting the results of his experiment we can realise the amount of creativity Thomson had to invest, because the idea of an electron was null. Through his experiment with cathode ray tubes, he determined a relation between mass and charge, measuring the deviation of a ray in a magnetic field. Thanks to this events, he realised that cathode rays were formed by particles, which he called corpuscles.

Then, his imagination went into a higher level, because he imagine atoms compound of a full sea of positive charges and corpuscles, which is called The Atomic Model of Thomson.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)