J. J. Thomson discovered electron by performing an experiment using cathode ray tubes. High voltage across is applied across two electrodes at that causes a beam of particles to flow from the the negatively-charged electrode that is cathode to the positively-charged electrode that is anode. Properties of the particles, are tested using two oppositely-charged electric plates around the cathode ray. The cathode ray was deflected away from the negatively-charged electric plate and towards the positively-charged plate. This indicated that the cathode ray was composed of negatively-charged particles. And these negatively charged particles are called electrons.
I believe that the answer is B
Yes, it's changing the appearance of the metal caused by rain, salt, or acid
When a volcano erupts magma comes from the top when the magma cools down it hardens and leaves a hard surface
