Line spectrum contains information about

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

$A$ 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....$eV$

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

An electron of a stationary hydrogen atom transitions from the fifth energy level to the ground level. The velocity that the atom acquires as a result of photon emission will be:

$Assertion :$ $A$ tube light emits white light.
$Reason :$ Emission of light in a tube takes place at a very high temperature.