Which of the following statements regarding cathode rays is incorrect?

Fill in the blanks given below:
$(i)$ The picture on the television screen is visible due to the presence of .......... on the screen.
$(ii)$ In the presence of electric and magnetic fields,cathode rays are known as .......... .
$(iii)$ The measurement of the $e/m_e$ ratio for electrons was performed by the scientist .......... .
$(iv)$ In a cathode ray tube,the greater the magnitude of the charge on the particles,the .......... the deflection of the particles.

Which of the following statements is incorrect regarding cathode rays?

Calculate the mass of $1$ mole of neutrons in $kg$. $\left( m_n = 1.675 \times 10^{-27} \ kg \right)$

The minimum real charge on any particle which can exist is

Positive charge in an atom is: