In accordance with Bohr’s model, what is the quantum number that characterizes the earth’s revolution around the sun in an orbit of radius $1.5\times {10}^{11} m$  with orbital speed $3\times {10}^4 m/s$? (Mass of earth = $6.0\times {10}^{24} kg.$)

1.  \(1.8\times 10^{76}\)
2. \(2.3 \times10^{74} \)
3. \(1.3 \times10^{76} \)
4. \(2.6 \times10^{74} \)

The total energy of an electron in the first excited state of the hydrogen atom is about \(-3.4\) eV. What is the kinetic energy of the electron in this state?
1. \(3.4\) eV
2. \(-3.4\) eV
3. \(3.2\) eV
4. \(-3.2\) eV

The total energy of an electron in the first excited state of the hydrogen atom is about -3.4 eV. What is the potential energy of the electron in this state?

1. 6.8 eV
2. -6.8 eV
3. 0
4. 3.4 eV

The ground state energy of a muonic hydrogen atom is:

(Mass of a negatively charged muon, $m_{\mu }=207 m_e$)

1. -2.07 keV
2. 2.81 keV
3. -2.81 keV
4. 2.07 keV

The minimum wavelength of \(X\text-\)rays produced by \(30 ~\text{kV}\) electrons is:
1. \(0.0414~\text{nm}\)
2. \(0.0041~\text{nm}\)
3. \(0.1410~\text{nm}\)
4. \(0.4140~\text{nm}\)

An \(X\text-\)ray tube produces a continuous spectrum of radiation with its short wavelength ending at  \(0.45~ \mathring{A}. \) What is the maximum energy of a photon in radiation?
1. \(27.6~ \text {keV} \)
2. \(25.5 ~\text {keV} \)
3. \(23.4 ~\text {keV} \)
4. \(25.1~ \text {keV}\)

The speed of the electron in a hydrogen atom in the \({n=1}\) level is:
1. \(1.1 \times10^{6} ~\text{m/s}\)
2. \(2.18 \times10^{6} ~\text{m/s}\)
3. \(1.08\times10^{6} ~\text{m/s}\)
4. \(3.07 \times10^{6} ~\text{m/s}\)

A hydrogen atom initially in the ground level absorbs a photon, which excites it to the \(n=4\) level. The wavelength of the photon is:

The radius of the innermost electron orbit of a hydrogen atom is \(5.3\times10^{-11}\) m. $\mathrm{}$What is the radius of the \(n=2\) orbit?
1. \(1.67 ~\mathring A\)
2. \(4.77~\mathring A\)
3. \(2.12~\mathring A\)
4. \(3.11~\mathring A\)

The ground state energy of the hydrogen atom is \(-13.6~ \text {eV}.\) What is the potential energy of the electron in this state?
1. \(-13.6~\text{eV}\)
2. \(27.2~\text {eV}\)
3. \(-27.2~ \text {eV}\)
4. \(13.6~\text {eV}\)