The colour of the positive column in a gas discharge tube depends on

If the ionisation potential of a helium atom is $24.6 \, V$,the energy required to ionise it will be

The graph between the square root of the frequency of a specific line of characteristic spectrum of $X$-rays and the atomic number of the target will be

Of the following pairs of species,which one will have the same electronic configuration for both members?

$A$ neutron moving with a speed $v$ makes a head-on collision with a stationary hydrogen atom in its ground state. The minimum kinetic energy of the neutron for which an inelastic collision will take place is....$eV$

The band spectra (characteristic of molecular species) is due to emission of radiation from which state of matter?