The graph between variation of probability density. $\psi^2(r)$ and distance of the electron from the nucleus, $r$ is shown below. This represents

The angular momentum of an electron in a stationary state of $\mathrm{Li}^{2+}(Z=3)$ is $3 h / \pi$. The radius and energy of that stationary state are respectively

Identify the pair of elements in which number of electrons in ( $n-1$ ) shell is same

In the ground state of hydrogen atom, electron absorbs 1.5 times energy than the minimum energy $\left(2.18 \times 10^{-18} \mathrm{~J}\right)$ to escape from the atom. The wavelength of the emitted electron (in $m$ ) is ( $m_e=9 \times 10^{-31} \mathrm{~kg}$ )