If an ideal monatomic gas is expanded adiabatically to twice its initial volume, what will the ratio of the final pressure to the initial pressure be

The correct option is the first one, which is: Negatively charged electrons.

 J.J Thomson was British physicist who discovered the electron in 1897, by his experiment with "cathode ray tubes". For this work and contribution to science, he was awarded the Nobel Prize for physics in 1906.