Which of the following represents the velocity of an electron in a hydrogen-like atom?

The ratio of minimum wavelengths of Lyman and Balmer series will be $:-$

The energy of an electron in the first Bohr orbit of $H$ atom is $-13.6 \ eV$. The possible energy value$(s)$ of the excited state$(s)$ for electrons in Bohr orbits of the hydrogen atom is(are) $............ \ eV$.

Radius of $1^{st}$ orbit of $H$ and some orbit of $Be^{3+}$ is same. Energy of their orbit of $Be^{3+}$ is ............$eV$.

The energy associated with the electron in the first orbit of a hydrogen atom is $-2.18 \times 10^{-18} \ J$. The frequency of the light required (in $Hz$) to excite the electron to the fifth orbit is $(h = 6.6 \times 10^{-34} \ Js)$

If the electron jumps from $7.00 \ eV$ energy level to $5.0 \ eV$ energy level,it :