Normally,the time taken in an electronic transition is approximately:

Which electron level would allow the hydrogen atom to absorb a photon but not emit a photon?

In a hydrogen atom,if an electron transitions from an $n$-th orbit to the ground state,and the total number of spectral lines observed is $10$,then the value of $n$ is:

If an atom has $x$ energy levels,what will be the total number of spectral lines in its emission spectrum?

Find the radius of the fourth orbit of a hydrogen atom if its radius of the first orbit is $R \text{ pm}$.

When an electron jumps from $n = 5$ to $n = 2$ with all possible transitions,which of the following statements is correct?