When a hydrogen atom is in its first excited level,its radius is .... of the Bohr radius.

For a certain hypothetical one-electron atom,the wavelength (in $\mathring{A}$) for the spectral lines for transition from $n = p$ to $n = 1$ is given by $\lambda = \frac{1500p^2}{p^2 - 1}$ (where $p > 1$). The ionization potential of this element must be .....$V$ (Take $hc = 12420\ eV\cdot\mathring{A}$).

In Bohr's model,the atomic radius of the first orbit is $r_0$,then the radius of the third orbit is

The wavelengths of the spectral lines in the spectrum of deuterium $(_{1}H^{2})$ differ slightly from those in the spectrum of hydrogen $(_{1}H^{1})$ because ...

Speed of an electron in Bohr's $7^{\text{th}}$ orbit for Hydrogen atom is $3.6 \times 10^6\,m/s$. The corresponding speed of the electron in $3^{\text{rd}}$ orbit,in $m/s$ is $........\times 10^6$.

Two electrons are moving in orbits of two hydrogen-like atoms with speeds $3 \times 10^5 \ m/s$ and $2.5 \times 10^5 \ m/s$ respectively. If the radii of these orbits are nearly the same,then the possible order of energy states are . . . . . . respectively.