The $1^{st}, 2^{nd},$ and $3^{rd}$ energy levels of an atom are $E, 4E/3,$ and $2E$ respectively. If a wavelength $\lambda$ is emitted during the transition $3 \to 1$,what is the wavelength emitted during the transition $2 \to 1$?

When an electron in a hydrogen atom jumps from the third orbit to the second orbit,it emits a photon of wavelength $\lambda$. When it jumps from the fourth orbit to the third orbit,the wavelength emitted by the photon will be

In an inelastic collision,an electron excites a hydrogen atom from its ground state to an $M$-shell state. $A$ second electron collides instantaneously with the excited hydrogen atom in the $M$-state and ionizes it. At least how much energy must the second electron transfer to the atom in the $M$-state?

What is the energy of the electron revolving in the third orbit expressed in $ eV $ (in $eV$)?

An electron makes a transition from an excited state to the ground state of a hydrogen-like atom. Out of the following statements,which one is correct?

Transitions between three energy levels in a particular atom give rise to three spectral lines of wavelengths $\lambda_1, \lambda_2$ and $\lambda_3$. Given that the wavelengths are in increasing order of magnitude,which one of the following equations correctly relates $\lambda_1, \lambda_2$ and $\lambda_3$?