The momentum of an electron revolving in the $n^{\text{th}}$ orbit is given by: (Symbols have their usual meanings)

In a hydrogen atom,an electron makes a transition from the $5^{\text{th}}$ orbit to the $3^{\text{rd}}$ orbit. The change in the angular momentum for this electron is . . . . . . .

The radius of the Bohr orbit in the ground state of a hydrogen atom is $0.5 \ \mathring{A}$. The radius of the orbit of the electron in the third excited state of $He^+$ will be ...... $\mathring{A}$.

According to the de Broglie hypothesis,if the de Broglie wavelength of an electron in a hydrogen atom orbit of radius $5.3 \times 10^{-11} \ m$ is $10^{-10} \ m$,then the principal quantum number of the electron is ..........

Which of the following graphs in the figure shows the speed $(v)$ of an electron in a hydrogen atom as a function of the principal quantum number $(n)$?

The radius of a hydrogen atom in its ground state is $5.3 \times 10^{-11} \ m$. After collision with an electron,it is found to have a radius of $21.2 \times 10^{-11} \ m$. What is the principal quantum number $n$ of the final state of the atom?