In $\mathrm{Sr}(Z=38)$, the number of electrons with $l=0$ is $x$, number of electrons with $l=2$ is $y \cdot(x-y)$ is equal to ( $l=$ Azimuthal quantum number)

The electron in hydrogen atom undergoes transition from higher orbits to an orbit of radius 476.1 pm . This transition corresponds to which of the following series?

Identify the incorrect statement from the following?

The radius of stationary state $(n=2)$ of hydrogen atom is $x \mathrm{pm}$. The radius of stationary state $(n=3)$ of $\mathrm{He}^{+}$ion (in pm) is