According to Stefan-Boltzmann law, the emissive power is directly proportional to the fourth powerof temperature. So, it will give a straight line.
An atom will have different radii depending on the bond it forms, so there is no fixed radius of an atom. Atomic Radii are therefore determined by the bonds they form.
Click here:point_up_2:to get an answer to your question :writing_hand:consider bohr theory for hydrogen atom the magnitude of angular momentum orbit radius and velocity