A hydrogen atom is excited to third energy. Determine the maximum & Minimum wavelength of its excitation. The ionisation potential of hydrogen atom is +13.6V.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?