Bohr’s model of atom

According to the Bohr Theory, among the following, which transition in the hydrogen atom will give rise to the least energetic photon?

The energy of the second Bohr orbit of the hydrogen atom is $-328 \mathrm{kJ} {\mathrm{mol}}^{-1}$. Hence, the energy of the fourth Bohr orbit would be

The Bohr orbit radius for the hydrogen atom (n = 1) is approximately  $0.530\AA .$  The radius for the first excited state (n = 2) orbit is  $(in\AA )$

The radius of hydrogen atom in the ground state is  $0.53\mathrm{\AA }.$  The radius of  ${\mathrm{Li}}^{2+}$ ion (Atomic number = $3$) in first orbit is

The electron was shown experimentally to have wave properties by

In hydrogen atom, the minimum energy required to excite an electron from $2^{\mathrm{nd} }$ orbit to the  $3^{\mathrm{rd} }$ orbit is

The total number of spectral lines observed when electron returns from the $6^{\mathrm{th}}$ shell until the $2^{\mathrm{nd}}$ shell in hydrogen atom is

According to Bohr theory, the electronic energy of a hydrogen atom in the ${\mathrm{n}}^{\mathrm{th}}$ Bohr atom is given by ${\mathrm{E}}_{\mathrm{n}}=\frac{21.76\times {10}^{-19}}{{\mathrm{n}}^2}\mathrm{J}$. Calculate the longest wavelength of light that will be needed to remove and electron from the third Bohr orbit of the ${\mathrm{He}}^{+}$ ion (If the wavelength is $x\times {10}^{-7}$(in meter) and $x$ is an integer. Report '$x$')

An element undergoes a reaction as shown:
$x+{\mathrm{e}}^{-}\to x^{-}$ energy released $=30.87 \mathrm{eV}$
If the energy released, is used to dissociate $12 \mathrm{g}$ of ${\mathrm{H}}_2$ molecules, equally into ${\mathrm{H}}^{+}$ and ${\mathrm{H}}^{*}$, where ${\mathrm{H}}^{*}$ is an excited state, in which the electron travels a path length equal to four times it's de-Broglie wavelength. Determine the least amount (in moles) of $\text{'}\mathrm{x}\text{'}$ that would be required.
Given: I.E. of $\mathrm{H}=13.6 \mathrm{eV}/\mathrm{atom}$, Bond energy of ${\mathrm{H}}_2=4.526 \mathrm{eV}/\mathrm{molecule}$.

In the Balmer series of atomic spectra of hydrogen, there is spectral line having wavelength $434.4 \mathrm{nm}$. Calculate the number of higher orbit from which the electron drops to generate this line. $\left(\mathrm{R}=10.97\times {10}^6 {\mathrm{m}}^{-1}\right)$

de-Broglie's wavelength of an electron having kinetic energy $2.7\times {10}^{-23} \mathrm{J}$ is $\mathrm{A}\times {10}^{-8} \mathrm{m}$. Then, what is the value of $\mathrm{A}$?

The de-Broglie wavelength of an electron travelling at $\mathrm{x}$percent of the speed of light was found to be $2.42 \stackrel{\mathrm{o}}{\mathrm{A}}$. Then, what is the value of '$\mathrm{x}$'?

The ratio of the velocity of ${\mathrm{SO}}_2$ molecules to the velocity of ${\mathrm{O}}_2$ molecules such that they are associated with de Broglie waves of the same wavelength is

Let the mass of a particle be $1 \mathrm{g}$ and its de-Broglie wavelength $6.63\times {10}^{-33} \mathrm{m}$. Then, what will be its velocity?

If the electron is accelerated by a potential difference of $300 \mathrm{V}$, then what will be wavelength associated with the moving electron?

Suppose the kinetic energy of a particle is doubled, de-Broglie's wavelength becomes