The approximate value of the principal quantum number for a circular orbit of a hydrogen atom of radius $530 \ nm$ is

The gravitational force between a $H$-atom and another particle of mass $m$ is given by Newton's law $F = G\frac{M m}{r^2}$. Here,$M$ represents:

When an electron jumps from the $n = 4$ level to the $n = 1$ level,the angular momentum of the electron changes by:

In the lowest energy level of a hydrogen atom,the electron has an angular momentum of:

An electron in an excited state of $Li^{2+}$ ion has angular momentum $\frac{3 h}{2 \pi}$. The de-Broglie wavelength of the electron in this state is $p \pi a_{0}$ (where, $a_{0} = \text{Bohr radius}$). The value of $p$ is

Energy required for the electron excitation in $Li^{++}$ from the first to the third Bohr orbit is.....$eV$