Which of the following provides evidence to support thomson's hypothesis about electrons?
gold foil experiment
cathode ray experiments
spectrum of colors emitted by gas
radiation produced when beryllium is bombarded with alpha particles

The answer is: Cathode ray experiments.

J.J. Thomson placed two oppositely charged electric plates around the cathode ray.

He did experiments using different metals as electrode materials and found that the properties of the cathode ray remained constant no matter what cathode material he used.

Tomson concluded that atoms are divisible and that the corpuscles are their building blocks (atoms are made up of smaller particles).  

J. J. Thomson discovered the electron in 1897.  

His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.

cathode ray experiment

Explanation:

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.