Which of the following particles cannot be accelerated by an electric or magnetic field?

In Millikan's experiment,static electric charge on the oil drops has been obtained by shining $X$-rays. If the static electric charge on the oil drop is $-1.282 \times 10^{-18} \ C,$ calculate the number of electrons present on it.

Among the following,the correct statement about the cathode ray discharge tube is:

What is a cathode ray discharge tube? Write down its uses.

The radius of the nucleus is related to the mass number $A$ by

The proton and neutron are collectively called as