Who discovered the charge of an electron? State the charge and mass of an electron.

When an electron particle strikes a $ZnS$ screen,it produces a flash of light (scintillation). What does this indicate?

The part of the atom excluding the outermost shell is known as the ...... .

The $\alpha$-particle is identical with

Electrons in a cathode ray tube have been emitted with a velocity of $1000 \, m \, s^{-1}$. The number of following statements which is/are true about the emitted radiation is
Given : $h = 6 \times 10^{-34} \, Js$,$m_{e} = 9 \times 10^{-31} \, kg$.
$(A)$ The de Broglie wavelength of the electron emitted is $666.67 \, nm$.
$(B)$ The characteristic of electrons emitted depend upon the material of the electrodes of the cathode ray tube.
$(C)$ The cathode rays start from cathode and move towards anode.
$(D)$ The nature of the emitted electrons depends on the nature of the gas present in cathode ray tube.

The volume of the atomic nucleus is $......$ of the volume of the atom.