When beryllium is bombarded with $\alpha$-particles,extremely penetrating radiations which cannot be deflected by electrical or magnetic field are given out. These are

Cathode rays are made up of

Are neutrons present in all atomic nuclei? Explain.

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

Identify the correct increasing order of $e/m$ ratio for the following particles: $n, p, e, \alpha$.

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.