Answer:
All are correct
Explanation:
a. when Thomson discovered electrons he called them copuscles.
b. Millikan calculated chage on electron which is -1.6022 x [tex]10^{-19}[/tex]C
c. Charge to mass ratio of electron is fixed that is 1.758820 x [tex]10^{11}[/tex]C/kg
d. Although electons have mass (9.1 x [tex]10^{-31}[/tex]kg) but is very small therefore it is not taken while calculating mass of atom.