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

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-rays produced by 30 kV electrons is:
1. 0.0414 nm
2. 0.0041 nm
3. 0.1410 nm
4. 0.4140 nm

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

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:
1. \(97\) nm
2. \(99\) nm
3. \(95\) nm
4. \(96\) nm

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 eV. What is the potential energy of the electron in this state?

1. -13.6 eV
2. 27.2 eV
3. -27.2 eV
4. 13.6 eV